**EXHIBIT 31.2****CERTIFICATION OF CHIEF FINANCIAL OFFICER**Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 I, JOHN L. SENNOTT, Jr., certify that:1. I have reviewed this Annual Report on Form 10-K of Darwin Professional Underwriters, Inc.(the “Registrant”);2. Based on my knowledge, this report does not contain any untrue statement of a material factor omit to state a material factnecessary to make the statements made, in light of the circumstances under which suchstatements were made, not misleadingwith respect to the period covered by this report;3. Based on my knowledge, the financial statements, and other financial information includedin this report, fairly present in allmaterial respects the financial condition, results of operations andcash flows of theRegistrant as of, and for, the periodspresented in this report;4. The Registrant’s other certifying officer and I are responsible for establishing andmaintaining disclosure controls andprocedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internalcontrol over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f))for the Registrant and we have:a. designed such disclosure controls and procedures, or caused such disclosure controls andprocedures to be designed under our supervision, to ensure that material information relatingto the Registrant, including its consolidated subsidiaries, is made known to us by otherswithin those entities, particularly during the period in which this report is being prepared;b. designed such internal control over financial reporting, or caused such internal controlover financial reporting to be designed under our supervision, to provide reasonableassurance regarding the reliability of financial reporting and the preparation of financialstatements for external purposes in accordance with generally accepted accounting principles;c. evaluated the effectiveness of the Registrant’s disclosure controls and procedures andpresented in this report our conclusions about the effectiveness of the disclosure controlsand procedures, as of the end of the period covered by this report based on suchevaluation; andd. disclosed in this report any change in the Registrant’s internal control over financialreporting that occurred during the Registrant’s most recent fiscal quarter that hasmaterially affected, or is reasonably likely to materially affect, the Registrant’s internalcontrol over financial reporting; and5. The Registrant’s other certifying officer and I have disclosed, based on our most recentevaluation of internal control over financial reporting, to the Registrant’s auditors and theaudit committee of Registrant’s board of directors (or persons performing the equivalentfunctions):a. all significant deficiencies and material weaknesses in the design or operation ofinternal control over financial reporting which are reasonably likely to adversely affect theRegistrant’s ability to record, process, summarize and report financial information; andb. any fraud, whether or not material, that involves management or other employees who have asignificant role in the Registrant’s internal control over financial reporting.        Date: February 23, 2007 /s/ John L. Sennott, Jr.   John L. Sennott, Jr. SVP and CFO