Document:

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                                                                 Exhibit 10.23.1

                              REINSURANCE AGREEMENT

                                  BY AND AMONG

                         PLATTE RIVER INSURANCE COMPANY
                                AS CEDING COMPANY
                                       AND
                        DARWIN NATIONAL ASSURANCE COMPANY
                                  AS REINSURER

                               DATED JULY 1, 2005

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                                TABLE OF CONTENTS

<TABLE>
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                                                                            PAGE
                                                                            ----
<S>                                                                         <C>
ARTICLE 1  DEFINITIONS ..................................................     1
ARTICLE 2  TERM .........................................................     2
ARTICLE 3  REINSURANCE CEDED ............................................     2
ARTICLE 4  EXTRA-CONTRACTUAL OBLIGATIONS ................................     3
ARTICLE 5  CONSIDERATION ................................................     3
ARTICLE 6  ADMINISTRATION ...............................................     4
ARTICLE 7  REPORTS AND RECONCILIATION ...................................     4
ARTICLE 8  RIGHT OF INSPECTION AND PARTICIPATION ........................     5
ARTICLE 9  THIRD PARTY REINSURANCE AGREEMENTS ...........................     5
ARTICLE 10 INDEMNIFICATION ..............................................     6
ARTICLE 11 COVENANTS ....................................................     6
ARTICLE 12 ERRORS AND OMISSIONS .........................................     7
ARTICLE 13 LEGAL PROCEEDINGS ............................................     8
ARTICLE 14 INSOLVENCY ...................................................     8
ARTICLE 15 REGULATORY APPROVALS .........................................     9
ARTICLE 16 TERMINATION ..................................................     9
ARTICLE 17 GENERAL PROVISIONS ...........................................     9
</TABLE>

                                        i

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                              REINSURANCE AGREEMENT

THIS REINSURANCE AGREEMENT (the "Reinsurance Agreement"), effective July 1,
2005, is made by and among Platte River Insurance Company, an insurance company
organized and existing under the laws of the State of Nebraska (the "Ceding
Company"), and Darwin National Assurance Company, an insurance company organized
and existing under the laws of the State of Delaware (the "Reinsurer" or
"Darwin"),

                                   WITNESSETH:

WHEREAS, the Ceding Company and Reinsurer are engaged in the property and
casualty insurance business;

WHEREAS, the Reinsurer desires to reinsure 100% of the Policy Liabilities (as
defined herein), effective on the Reinsurance Effective Date (as defined
herein); and

WHEREAS, the Ceding Company desires to have the Reinsurer reinsure the Policy
Liabilities, effective on the Reinsurance Effective Date,

NOW, THEREFORE, for and in consideration of the foregoing premises and the
promises and the mutual agreements hereinafter set forth, the parties hereto
agree as follows:

                                    ARTICLE 1

                                   DEFINITIONS

As used in this Reinsurance Agreement, the following terms shall have the
following respective meanings:

"Affiliate" means, with respect to any Person, at the time in question, any
other Person directly or indirectly controlling, controlled by or under common
control with such Person.

"Applicable Law" means any federal, state or local statute, law, ordinance,
regulation, order, writ, injunction, directive, judgment or decree applicable to
the parties hereto, or any of their respective Affiliates, properties, or
assets, as the case may be.

"Books and Records" means all records, documents, data and information, in any
form whatsoever, including, but not limited to, hard copies, computer tapes and
drives, CD-ROM or other physical or electronic media, relating to the Policy
Liabilities, including all such materials relating to any third party
reinsurance relating to such Policy Liabilities.

"Business Day" means any day other than a Saturday, Sunday, a day on which
banking institutions in either of the States of Wisconsin or Connecticut are
permitted or obligated by law to be closed or a day on which the New York Stock
Exchange is closed for trading.

"Extra Contractual Obligations" means all liabilities for compensatory,
consequential, exemplary, punitive, statutory or similar damages which relate to
or arise (i) in connection with any alleged or actual act, error or omission by
the Ceding Company or any of its Affiliates

<PAGE>

relating to the Policy Liabilities and/or the Policies, or (ii) in connection
with any such alleged or actual act, error or omission by the Reinsurer acting
on behalf of Ceding Company or any of its Affiliates.

"Loss or Losses" mean all claims, judgments, awards, losses, liabilities,
obligations, damages, payments, deficiencies, costs or expenses (including
allocated loss adjustment expenses), including, without limit, any penalties and
attorneys' fees and disbursements.

"Person" means any individual, corporation, partnership, firm, joint venture,
association, company, trust, unincorporated organization, governmental, judicial
or regulatory body, business unit division or other entity.

"Policy Liabilities" means all Losses (net of reinsurance payments actually
received by Ceding Company from reinsurers not affiliated with Ceding Company)
arising out of or relating to policies written through Darwin Professional
Underwriters, Inc. ("DPU") on Ceding Company paper pursuant to an Underwriting
Management Agreement between DPU and Ceding Company effective June 1, 2003 and
not otherwise ceded by Ceding Company to Darwin National Assurance Company or
otherwise paid by the Ceding Company prior to the Reinsurance Effective Date
(the "Policies").

"Policy Reserves" means the reserves of Ceding Company as of the Reinsurance
Effective Date with respect to the Policy Liabilities without giving effect to
this Reinsurance Agreement.

"Reinsurance Effective Date" shall be July 1, 2005.

"Tax or Taxes" means reinsurance premium taxes, reinsurance excise taxes, second
injury fund assessments (net of reimbursements, if any), guarantee fund
assessments (net of premium tax credits as used) or any other similar
premium-based taxes or similar assessments directly arising from, or directly
relating to, the Policy Liabilities, including any interest, penalties or
additions attributable thereto.

                                    ARTICLE 2

                                      TERM

Subject to all of the provisions set forth herein, this Reinsurance Agreement
shall be effective as of the Reinsurance Effective Date and shall remain in
effect so long as there are any outstanding Policy Liabilities or until this
Reinsurance Agreement is terminated in accordance with the provisions of Article
16 hereof.

                                    ARTICLE 3

                                REINSURANCE CEDED

A.   The Ceding Company hereby cedes, and the Reinsurer hereby accepts and
     assumes, as of the Reinsurance Effective Date, one hundred percent (100%)
     of the Policy Liabilities incurred by the Ceding Company, including any
     Taxes.

                                        2

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B.   The Ceding Company will use reasonable efforts to provide to the Reinsurer
     available information relating to the Policy Liabilities. Failure to
     provide any such information, or include any claim, policy form or other
     information relating to the Policy Liabilities, shall not affect the
     reinsurance coverage provided for by this Reinsurance Agreement.

C.   Neither the Ceding Company nor the Reinsurer shall have the right to
     commute the reinsurance ceded under this Reinsurance Agreement, except
     pursuant to the provisions of paragraph B of Article 16 of this Reinsurance
     Agreement.

D.   The Reinsurer shall follow the fortunes of the Ceding Company for all
     Policy Liabilities and matters covered by this Reinsurance Agreement in all
     respects, and the Reinsurer shall be bound by all payments and settlements
     entered into by the Ceding Company and/or DPU on behalf of the Ceding
     Company.

                                    ARTICLE 4

                          EXTRA-CONTRACTUAL OBLIGATIONS

The Reinsurer shall pay and be responsible for 100% of any Extra Contractual
Obligations arising out of or relating to the Policy Liabilities.

                                    ARTICLE 5

                                  CONSIDERATION

A.   The Ceding Company will compute and credit the amount due to the Reinsurer
     in consideration for the reinsurance provided hereunder a sum equal to the
     June 30, 2005 GAAP book value of the loss and loss adjustment expense
     reserves and unearned premium, less any deferred acquisition expense
     related to the unearned premium, for the Policies, less any ceded unearned
     premiums and reinsurance receivables from unaffiliated reinsurers on paid
     and unpaid Losses for the Policies. In addition to any other amounts due
     Ceding Company, Reinsurer shall reimburse Ceding Company for any and all
     amounts paid and/or payable by Ceding Company to DPU under the Underwriting
     Management Agreement between DPU and Ceding Company effective December 12,
     2003.

B.   Within fifteen (15) business days following the Reinsurance Effective Date,
     the Ceding Company will remit to the Reinsurer the consideration to be
     calculated pursuant to paragraph A of this Article. The form of the total
     consideration may include reinsurance recoverables relating to business
     reinsured (credited at full GAAP book value), cash, and invested assets of
     the entities reinsured (as determined by the Ceding Company and credited at
     market value). All invested assets transferred shall be free and clear of
     all claims, liens and encumbrances. The Ceding Company and the Reinsurer
     may, upon mutual agreement, offset amounts due under this Agreement against
     other amounts due between the parties.

C.   The Reinsurer shall be entitled, as a reinsurance premium, to 100% of all
     collected premiums, salvage and subrogation and any other moneys received
     by the Ceding

                                        3

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     Company with respect to the Policies after the Reinsurance Effective Date,
     except for any amount received by Ceding Company for reinsurance
     recoverables not transferred to the Reinsurer. Any costs, expenses and
     commissions incurred in collecting the amounts set forth in this paragraph
     D shall be borne by the Reinsurer.

D.   The Reinsurer shall fully reimburse the Ceding Company for any and all
     losses and expenses (including collection expenses and attorney's fees)
     arising from the failure of an unaffiliated reinsurer to timely pay the
     Ceding Company amounts due the Ceding Company in connection with the
     business covered by this Agreement.

                                    ARTICLE 6

                                 ADMINISTRATION

In further consideration of the mutual promises under this Reinsurance
Agreement, the Ceding Company and the Reinsurer agree that the Policy
Liabilities will be administered by the Reinsurer provided, however, that
Reinsurer may permit DPU to provide administrative services related to these
Policy Liabilities in the same manner and to the same extent that DPU provides
such services on business written by Ceding Company through DPU. However,
notwithstanding the performance of such services by DPU, Reinsurer shall remain
directly liable for the performance of such services and Ceding Company shall
not be required to compensate DPU in any manner for such services performed as
permitted under this Reinsurance Agreement.

                                    ARTICLE 7

                           REPORTS AND RECONCILIATION

A.   Periodically, within a time frame as mutually agreed upon by the parties,
     during the term of this Reinsurance Agreement, there shall be transmitted
     by the Reinsurer to the Ceding Company, in form and substance mutually
     agreed upon by the parties, a "summary report" for the period reported on,
     of all activity relating to the Policy Liabilities. The report shall
     include, but not be limited to, the amount of gross premiums, commissions,
     related expenses, reserves and paid losses, as applicable. The report shall
     also reconcile any amounts due the Ceding Company and Reinsurers under this
     Reinsurance Agreement.

B.   Except to the extent that this Reinsurance Agreement provides otherwise,
     all amounts shall be paid within twenty (20) Business Days of delivery of
     such report, and any amount not paid within such twenty (20) Business Day
     period shall bear simple interest at the 60-Day C.P. Rate (as such rate is
     published under the caption "Commercial Paper" for a 60-Day duration in
     Federal Reserve Statistical Release H.15 (519) on the date the payment is
     made) (the " 60-Day C.P. Rate") from the twentieth Business Day until the
     date of payment.

C.   To the extent Reinsurers has reasonably available the applicable
     information, or such information as can reasonably be made available,
     Reinsurers shall prepare all reports reasonably requested by the Ceding
     Company in connection with tile Policy Liabilities to

                                        4

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     enable the Ceding Company to comply with any contractual requirements, any
     and all Applicable Laws including, without limitation, all statutory
     insurance reporting requirements and, as the case may be, reasonable
     informational or reporting requests from reinsurers. Any monthly or
     quarterly reports required to be prepared by Reinsurers shall be prepared
     within fifteen (15) Business Days following the last day of the applicable
     month or calendar quarter, as the case may be. Any year-end reports and
     reports for the Ceding Company's reinsurers required to be prepared by
     Reinsurers shall be prepared on a timely basis in order for the Ceding
     Company to comply with any filing deadlines required by law or by contract.
     All such reports shall include such information as may reasonably be
     required by the Ceding Company.

                                    ARTICLE 8

                      RIGHT OF INSPECTION AND PARTICIPATION

To the extent permitted by Applicable Law, from the date hereof until the date
on which Reinsurer has fulfilled all of its obligations to the Ceding Company
under this Reinsurance Agreement, and at any time (without limitation) as may be
required in the Ceding Company's judgment in order for the Ceding Company to
comply with any Applicable Law or to perform its obligations or responsibilities
under this Reinsurance Agreement, the Ceding Company and its authorized
representatives may from time to time reasonably request, and Reinsurer shall
provide, during normal business hours, full and open access to examine all Books
and Records under the control of Reinsurer relating to the Policy Liabilities
and to discuss the Policy Liabilities or the reinsurance provided under this
Reinsurance Agreement with the employees and agents of Reinsurer who are
familiar therewith, so that the Ceding Company shall have sufficient opportunity
to make whatever investigation it shall reasonably deem necessary and desirable
in connection with the transactions contemplated by this Reinsurance Agreement.
Such access and opportunity shall be exercised by the Ceding Company and such
authorized representatives in a manner that shall not interfere unreasonably
with the operations of Reinsurer. Such access shall include provision by
Reinsurer to the Ceding Company of copies of any Books and Records to the extent
that the Ceding Company reasonably determines that it requires copies of any
such Books and Records in order to carry out the transactions contemplated by
this Reinsurance Agreement or for any legitimate business purposes related to
this Reinsurance Agreement.

                                    ARTICLE 9

                       THIRD PARTY REINSURANCE AGREEMENTS

A.   Future potential recoveries under reinsurance contracts providing aggregate
     limits shall be apportioned pursuant to generally accepted allocation
     practices or procedures; provided that the method or the combination of
     methods actually utilized shall be reasonable and equitable; provided,
     further, that if the Ceding Company and the Reinsurer do not agree on any
     allocation, such dispute shall be subject to resolution pursuant to Article
     13 hereof.

                                        5

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B.   Nothing in this Agreement shall be deemed a warranty or guaranty by the
     Ceding Company of the reinsurance recoverables transferred to the Reinsurer
     pursuant to Article 5 hereof.

                                   ARTICLE 10

                                 INDEMNIFICATION

A.   The Reinsurer agrees to indemnify, defend and hold harmless the Ceding
     Company and its directors, officers, employees, successors and permitted
     assigns from and against all Losses arising under or related to the Policy
     Liabilities assumed by the Reinsurer under this Reinsurance Agreement and
     the Extra Contractual Obligations assumed by the Reinsurer pursuant to
     Article 4 hereof.

B.   In the event the Ceding Company (or its directors, officers, employees,
     successors and permitted assigns) shall have a claim for indemnity against
     the Reinsurer, the Ceding Company shall deliver written notice of such
     claim with reasonable promptness to the Reinsurer specifying in reasonable
     detail the facts constituting the basis for and the amount of, the claim
     asserted. The failure by the Ceding Company to notify the Reinsurer shall
     not relieve the Reinsurer from any liability that it may have to the Ceding
     Company with respect to any claim made pursuant to this Article 10. The
     Ceding Company shall have authority to select counsel and control all
     aspects of the defense of any matters subject to this Article 10, subject
     to the approval of the Reinsurer, not to be unreasonably withheld.

                                   ARTICLE 11

                                    COVENANTS

A.   The Reinsurer shall maintain Policy Reserves consistent with the law of any
     jurisdiction having regulatory authority with respect to the Policy
     Liabilities.

B.   The Reinsurer shall, at its own expense, take all steps necessary to ensure
     that the Ceding Company obtain full financial statement credit in all
     applicable jurisdictions for the reinsurance ceded under this Reinsurance
     Agreement, including, to the extent required, the posting of letters of
     credit or other acceptable security.

C.   Notwithstanding any other provision of this Agreement to the contrary, if
     the Reinsurer becomes unauthorized in any State or Commonwealth of the
     United States of America or the District of Columbia or any other
     jurisdiction where authorization is required by insurance regulatory
     authorities in order for the Ceding Company to obtain credit on its
     statutory annual statements for the reinsurance being provided under this
     Reinsurance Agreement, the Reinsurer will establish such escrow accounts,
     trust accounts for the benefit of the Ceding Company, letters of credit, or
     a combination thereof as required by Applicable Law to permit the Ceding
     Company to obtain Credit for such reinsurance upon the request of the
     Ceding Company if a penalty Would accrue to the Ceding

                                        6

<PAGE>

     Company on its statutory annual statement without such funding. The Ceding
     Company shall have the option of determining the method of funding to be
     utilized.

     The Reinsurer shall promptly notify the Ceding Company of any loss of
     license or authorization or other change or condition which, in the
     reasonable judgment of the Ceding Company, may affect the ability of the
     Ceding Company to obtain credit on its statutory financial statements for
     such reinsurance.

D.   In the event (a) the Reinsurer is required to file a "Company Action Plan"
     as a result of its risk based capital level falling below required levels,
     which condition is not promptly cured by the Reinsurer upon notice by the
     Ceding Company, or (b) the AM Best rating of the Reinsurer falls below an
     "A-", the Reinsurer shall promptly collateralize its reinsurance
     obligations to the Ceding Company under this Reinsurance Agreement in a
     manner reasonably satisfactory to the Ceding Company. Such
     collateralization shall only be required during the period in which the
     Reinsurer's risk based capital level is below required levels under
     Applicable Law or (b) of the prior sentence applies.

E.   The Reinsurer shall promptly notify the Ceding Company of the occurrence of
     any of the following events:

     a.   As a result of the Reinsurer's risk based capital falling below
          required levels, the Reinsurer is required to file a "Company Action
          Plan" or (b) the AM Best rating of the Reinsurer falls below an "A-".

     b.   The insolvency of the Reinsurer or the existence of any condition that
          would provide grounds for the commencement of a rehabilitation,
          conservation, liquidation or other delinquency proceedings by a
          governmental entity with respect to the Reinsurer.

F.   The Reinsurer shall, within twenty (20) Business Days of notification by
     the Ceding Company, pay all Taxes.

                                   ARTICLE 12

                              ERRORS AND OMISSIONS

Any delays, errors or omissions on the part of one party occurring in connection
with its obligations under this Reinsurance Agreement or any transaction
hereunder shall not relieve any other party from any liability which would have
otherwise attached had such delay, error or omission not occurred, provided that
such error or omission is rectified as soon as reasonably practicable after
discovery thereof. Notwithstanding the foregoing, no inadvertent failure by the
Ceding Company to give notice to the Reinsurer of a claim or occurrence relating
to the Policy Liabilities being reinsured hereunder, regardless of prejudice to
the Reinsurer, shall render unenforceable or void the reinsurance relating to
such claim being provided under this Reinsurance Agreement.

                                        7

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                                   ARTICLE 13

                                LEGAL PROCEEDINGS

Each of the parties hereto agrees that any legal action or proceeding with
respect to this Reinsurance Agreement shall be brought in the Courts of the
State of Wisconsin, or the United States District Court for the Western District
of Wisconsin and, by execution and delivery of this Reinsurance Agreement, each
party hereto irrevocably submits itself in respect of its property, generally
and unconditionally, to the jurisdiction of the aforesaid courts in any legal
action or proceeding arising out of this Reinsurance Agreement. Each of the
parties hereto hereby irrevocably waives any objection which it may now or
hereafter have to the laying of venue of any of the aforesaid actions or
proceedings arising out of or in connection with this Reinsurance Agreement
brought in the courts referred to in the preceding sentence. Each party hereby
consents to process being served in any such action or proceeding by the mailing
of a copy thereof to the address set forth in Article 17 (M) hereof and agrees
that such service upon receipt shall constitute good and sufficient service of
process or notice thereof. Nothing herein shall affect or eliminate any right to
serve process in any other matter permitted by law.

                                   ARTICLE 14

                                   INSOLVENCY

In the event of the insolvency, liquidation or rehabilitation of the Ceding
Company or the appointment of a liquidator, receiver or statutory successor of
the Ceding Company, the reinsurance coverage provided hereunder shall be payable
by the Reinsurer directly to the Ceding Company or to its liquidator, receiver
or statutory successor, on the basis of the liability of the Ceding Company for
the Policy Liabilities without diminution because of such insolvency,
liquidation, rehabilitation or appointment or because such liquidator, receiver
or statutory successor has failed to pay any or a portion of any claims. In any
such event, the reinsurance being provided hereunder shall be payable
immediately upon demand, with reasonable provision for verification, on the
basis of claims allowed against the Ceding Company by any court of competent
jurisdiction or by any liquidator, receiver or statutory successor. In any such
event, the liquidator, receiver or statutory successor of the Ceding Company
shall give written notice to the Reinsurer of the pendency of each claim against
the Ceding Company with respect to such Policy Liabilities within a reasonable
time after each such claim is filed in the insolvency, liquidation or
rehabilitation proceeding. During the pendency of any such claims, the Reinsurer
may, at its own expense, investigate such claim and interpose in the proceeding
in which such claim is to be adjudicated any defense or defenses, which the
Reinsurer may reasonably deem available to the Ceding Company or its liquidator,
receiver or statutory successor. The expenses incurred in connection therewith
by the Reinsurer shall be chargeable, subject to court approval, against the
Ceding Company as part of the expense of such insolvency, liquidation or
rehabilitation to the extent of any benefit, which accrues to the Ceding
Company, solely as a result of the defense or defenses undertaken by the
Reinsurer.

                                        8

<PAGE>

                                   ARTICLE 15

                              REGULATORY APPROVALS

A.   It shall be a condition to the effectiveness of this Reinsurance Agreement
     that the Ceding Company and the Reinsurer shall have obtained prior
     approval of this Reinsurance Agreement from those state insurance
     departments or other regulatory authorities, the approval of which is
     required for the effectiveness of this Reinsurance Agreement.

B.   At all times during the term of this Reinsurance Agreement, Reinsurers
     shall hold and maintain all licenses and authorities required under
     Applicable Laws to perform its obligations hereunder.

                                   ARTICLE 16

                                   TERMINATION

A.   This Reinsurance Agreement shall be terminated:

     1.   upon the termination of all of the Policy Liabilities;

     2.   by mutual written agreement of the parties; or

     3.   at the option of the Ceding Company, upon the occurrence of the
          commencement of a rehabilitation, liquidation, conservation or other
          delinquency proceeding against the Reinsurers, or the existence of any
          condition (continuing as of the date of termination) that would
          provide reasonable grounds for the commencement of a rehabilitation,
          liquidation, conservation or other delinquency proceeding against the
          Reinsurers, under applicable state insurance laws and regulations,
          which condition is not promptly cured by the Reinsurer upon notice by
          the Ceding Company of its intent to exercise its rights under this
          provision.

B.   In the event of the termination of this Reinsurance Agreement under
     paragraph A (3) of this Article, the Ceding Company shall be permitted, at
     its sole option, to commute the Policy Liabilities. In such an event, the
     Reinsurer shall transfer to the Ceding Company, subject to any necessary
     court approval, assets with a fair market value equal to the Policy
     Liabilities subject to such commutation as of the effective date of the
     commutation ("Commutation Payment"). All parties shall use their best
     efforts to cooperate in effectuating the necessary transitions.

                                   ARTICLE 17

                               GENERAL PROVISIONS

A.   Invalidity. Unless the invalidity or unenforceability of any provision or
     portion thereof frustrates the intent of the parties or the purpose of this
     Reinsurance Agreement, such invalidity or unenforceability shall not affect
     the validity or enforceability of the other provisions or portions thereof.
     In the event that such provision shall be declared

                                        9

<PAGE>

     unenforceable by a court of competent jurisdiction, such provision or
     portion thereof, to the extent declared unenforceable, shall be stricken.
     However, in the event any such provision or portion thereof shall be
     declared unenforceable due to its scope, breadth or duration, then it shall
     be modified to the scope, breadth or duration permitted by law and shall
     continue to be fully enforceable as so modified.

B.   Entire Agreement. This Reinsurance Agreement constitutes the entire
     contract between the parties with respect to the reinsurance and
     administration of the Policy Liabilities and there are no understandings
     between the parties as to the reinsurance or administrative services to be
     provided other than as expressed in this Reinsurance Agreement and the
     Administrative Services Agreement. Any amendment or modification hereto
     shall be null and void unless made in writing by amendment to this
     Reinsurance Agreement and executed by all parties.

C.   Governing Law. This Reinsurance Agreement shall be deemed to have been made
     under and governed by the laws of the State of Wisconsin without regard to
     Wisconsin's choice of law rules.

D.   Counterparts. This Reinsurance Agreement may be executed in two or more
     counterparts, each of which shall be deemed all original, but all of which
     together shall constitute one and the same instrument. This Reinsurance
     Agreement shall become effective when one or more counterparts have been
     signed by each party hereto and delivered to the other parties hereto,
     which consent shall not unreasonably be withheld.

E.   No Third Party Beneficiaries. Nothing in this Reinsurance Agreement is
     intended or shall be construed to give any Person, other than the parties
     hereto, any legal or equitable right, remedy or claim under or in respect
     of this Reinsurance Agreement or any provision contained herein; provided,
     however, that any person entitled to indemnification pursuant to Article 10
     hereof shall be entitled to enforce such article.

F.   Assignment. This Reinsurance Agreement shall be binding upon and inure to
     the benefit of the parties hereto and their respective successors and
     assigns and legal representatives. This Reinsurance Agreement is not
     assignable except by operation of law or by mutual written consent of the
     parties hereto.

G.   Waivers. The terms of this Reinsurance Agreement may be waived only by a
     written instrument signed by the party waiving compliance. No delay on the
     part of any party in exercising any right, power or privilege hereunder
     shall operate as a waiver thereof. Nor shall any waiver on the part of any
     party of any right, power or privilege, nor any single or partial exercise
     of any such right, power or privilege, preclude any further exercise
     thereof or the exercise of any other such right, power or privilege.

H.   Headings. The headings in this Reinsurance Agreement are for the
     convenience of reference only and shall not affect its interpretation.

I.   Exhibits. Each Exhibit referred to herein is incorporated into this
     Reinsurance Agreement by such reference.

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<PAGE>

J.   Preparation. This Reinsurance Agreement has been jointly prepared by the
     parties hereto and the terms hereof will not be construed in favor of or
     against any such party by reason of its participation in such preparation.

K.   Reasonableness. Each of the Parties will act reasonably and in good faith
     on all matters within the terms of this Reinsurance Agreement.

L.   Incontestability. In consideration of the mutual covenants and agreements
     contained herein, each party hereto does hereby agree that this Reinsurance
     Agreement, and each and every provision hereof, is and shall be enforceable
     by and between them according to its terms, and each party does hereby
     agree that it shall not contest the validity or enforceability hereof.

M.   Notices. All notices, requests, demands, approvals and other communications
     under this Reinsurance Agreement shall be in writing and shall he delivered
     personally, sent by facsimile transmission or sent by certified, registered
     or express mail, postage prepaid. Any such notice or other communication
     shall be deemed given upon actual delivery if presented personally or sent
     by facsimile transmission, in each case to the following addresses:

     If to the Ceding Company:

     Chief Financial Officer
     Capitol Insurance Companies
     4610 University Avenue
     P.O. Box 5900
     Madison, WI 53705-0900
     Fax: 608-231-2053

     With copies to:

     General Counsel
     Capitol Insurance Companies
     4610 University Avenue
     P.O. Box 5900
     Madison, WI 53705-0900
     Fax: 608-231-2053

     If to Reinsurer:

     Chief Financial Officer
     Darwin National Assurance Company
     9 Farm Springs Road
     Farmington, CT 06032
     Fax: 860-284-1301

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<PAGE>

     With copies to:

     General Counsel
     Darwin National Assurance Company
     9 Farm Springs Road
     Farmington, CT 06032
     Fax: 860-284-1950

Any party may, by notice given in accordance with this Reinsurance Agreement to
the other parties, designate another address, fax number or person for receipt
of notices hereunder.

N.   Offsets: Ceding Company and Reinsurers play offset any balance, whether on
     account of premiums, commissions, losses or claim expenses, due from one
     party to the other under this Reinsurance Agreement or under any other
     reinsurance agreement hereafter entered into between Ceding Company and
     Reinsurer, provided, however, that in the event of the insolvency,
     liquidation, or rehabilitation of a party hereto, offsets shall only be
     permitted to the extent allowed under the terms of this Reinsurance
     Agreement and applicable law,

     IN WITNESS WHEREOF, and intending to be legally bound, the parties have
signed this Reinsurance Agreement.

                                        PLATTE RIVER INSURANCE COMPANY

Date 8/1/05                             By: /s/ David F. Pauly
     -------------------                    ------------------------------------
                                        Name: David F. Pauly
                                              ----------------------------------
                                        Title: President
                                               ---------------------------------

                                        DARWIN NATIONAL ASSURANCE COMPANY

Date 8/31/05                            By: /s/ John L. Sennott, Jr.
     -------------------                    ------------------------------------
                                        Name: John L. Sennott, Jr.
                                              ----------------------------------
                                        Title: CFO
                                               ---------------------------------

                                       12<PAGE>
                                                                 Exhibit 10.23.2

                                    AMENDMENT
                                     TO THE
                              REINSURANCE AGREEMENT
                                      AMONG

Platte River Insurance Company (hereinafter referred to as the "Ceding Company")
and Darwin National Assurance Company (hereinafter referred to as "Reinsurer" or
"Darwin").

WHEREAS, the parties desire to modify certain terms and conditions of the
Reinsurance Agreement between the parties dated July 1, 2005;

NOW, THEREFORE, for the consideration mentioned and other good and valuable
consideration, the receipt and sufficiency of which is hereby acknowledged, the
parties do agree as follows:

      1.    The parties hereby agree that the effective date for the Agreement
            shall be October 1, 2005 instead of the previously referenced July
            1, 2005.

      2.    The definition of Reinsurance Effective Date in Article I is hereby
            amended in its entirety as follows:

            "Reinsurance Effective Date" shall be October 1, 2005.

      3.    Article 5 (A) is hereby amended in its entirety as follows:

            The Ceding Company will compute and credit the amount due to the
            Reinsurer in consideration for the reinsurance provided hereunder a
            sum equal to the September 30, 2005 GAAP book value of the loss and
            loss adjustment expense reserves and unearned premium, less any
            deferred acquisition expense related to the unearned premium, for
            the Policies, less any ceded unearned premiums and reinsurance
            receivables from unaffiliated reinsurers on paid and unpaid Losses
            for the Policies. In addition to any other amounts due Ceding
            Company, Reinsurer shall reimburse Ceding Company for any and all
            amounts paid and/or payable by Ceding Company to DPU under the
            Underwriting Management Agreement between DPU and Ceding Company
            effective December 12, 2003.

      4.    Article 5 (B) is hereby amended in its entirety as follows:

            By December 31, 2005, the Ceding Company will remit to the Reinsurer
            the consideration to be calculated pursuant to paragraph A. of this
            Article. The form of the total consideration may include reinsurance
            recoverables relating to business reinsured (credited at full GAAP
            book value), cash, and invested assets of the entities reinsured (as
            determined by the Ceding Company and credited at market value). All
            invested assets transferred shall be free and clear of all claims,
            liens and encumbrances. The Ceding Company and the Reinsurer may,
            upon
<PAGE>
            mutual agreement, offset amounts due under this Agreement against
            other amounts due between the parties.

      5.    This Amendment may be executed in counterparts of like form, each of
            which, when executed, shall be deemed together an original and all
            of which taken together shall constitute one and the same
            instrument.

      6.    Except as hereby amended, the terms and provisions of the Agreement
            shall remain in full force and effect. This Amendment shall be
            effective as of the inception of the Agreement.

IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed
and delivered by their duly authorized representatives.

<Table>
<S>                                                     <C>
Darwin National Assurance Company                       Platte River Insurance Corporation

By: /s/ John L. Sennott, Jr.                            By: /s/ David F. Pauly
    ______________________________________________          ________________________________________

Name: John L. Sennott, Jr.                              Name: David F. Pauly
      ____________________________________________            ______________________________________

Title: CFO                                              Title: President
       ___________________________________________             _____________________________________
</Table>

                                      -2-

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