# UNITED STATESSECURITIES
AND EXCHANGE COMMISSIONWASHINGTON, D.C. 20549

# FORM 20-F/A (Amendment No. 1)

(Mark One)

|/ / |  | REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF
1934
|--- |  | ----------------------------------------------------------------------------------------------

OR

|X |  | ANNUAL
REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the
fiscal year ended 31 December 2003
|- |  | -------------------------------------------------------------------------------------------------------------------------------

OR

|/ / |  | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
     For the transition period from       to
|--- |  | -------------------------------------------------------------------------------------------------------------------------------------

Commission file number
0-28970

COLT Telecom Group plc (Exact
name of Registrant as specified in its charter)

England (Jurisdiction of
incorporation or organization)

Beaufort House, 15 St. Botolph
Street, London EC3A 7QN, England (Address of principal executive offices)

Securities registered or to be
registered pursuant to Section 12(b) of the Act:  None

Securities registered or to be
registered pursuant to Section 12(g) of the Act:

| | American
Depositary Shares, each representing the right to receive four Ordinary Shares, nominal
value 2.5p each;  Ordinary Shares, nominal value 2.5p each Warrants
to purchase Ordinary Shares, nominal value 2.5p each; and 2% Senior Convertible
Notes due 2005.
| | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Securities for which there is a
reporting obligation pursuant to Section 15(d) of the Act: None

Indicate the number of outstanding
shares of each of the issuers classes of capital or common stock as of the close of
the period covered by the annual report:

| | 1,510,153,743
Ordinary Shares, nominal value 2.5p each
| | ------------------------------------------------------

Indicate by check mark whether the
Registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the
Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period
that the registrant was required to file such reports) and (2) has been subject to such
filing requirements for the past 90 days.   X Yes     / / No

Indicate by check mark which
financial statement item the registrant has elected to follow.   / / Item 17      X  Item 18

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# Explanatory Note

This Form 20-F/A has been filed to
amend and restate Exhibits 12.1 and 12.2 to our Form 20-F filed on April 30, 2004 in order
to make certain corrections in the certifications required by Rule 13a-14(a)/15d-14(a) of
the Securities Exchange Act of 1934, as amended. This Form 20-F/A consists of a cover
page, this explanatory note and the above described exhibits. This Form 20-F/A does not
update or restate any information in our Form 20-F filed on April 30, 2004 other than
Exhibits 12.1 and 12.2 or reflect any events that have occurred after the Form 20-F was
filed.

# Item 19.   Exhibits

|Exhibit Number | Exhibit                                                                                                                                                                                           
|-------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|12.1           | Certification
Required by Rule 13a-14(a)/15d-14(a) of the Securities Exchange Act of 1934, as amended,
as adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. (Furnished
herewith.)
|12.2           | Certification
Required by Rule 13a-14(a)/15d-14(a) of the Securities Exchange Act of 1934, as amended,
as adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. (Furnished
herewith.)

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# SIGNATURES

Pursuant to the requirements of
Section 12 of the Securities Exchange Act 1934, the Registrant certifies that it meets all
of the requirements for filing on Form 20-F and has duly caused this amendment to the
annual report to be signed on its behalf by the undersigned thereunto duly authorised.

COLT Telecom Group plc (Registrant)

By:  /s/  Jane Forrest
                                       Jane Forrest Company Secretary

Dated: 22 July 2004

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