SCHEDULE 13G

Amendment No. 6
COLT Telecom Group Plc
Ordinary Shares
Cusip # G22944121

Cusip # G22944121
Item 1:	Reporting Person - FMR Corp.
Item 4:	Commonwealth of Massachusetts
Item 5:	345,845,160
Item 6:	0
Item 7:	345,845,160
Item 8:	0
Item 9:	345,845,160
Item 11:	49.35%
Item 12:	    HC

Cusip # G22944121
Item 1:	Reporting Person - Edward C. Johnson 3d
Item 4:	United States of America
Item 5:	0
Item 6:	0
Item 7:	345,845,160
Item 8:	0
Item 9:	345,845,160
Item 11:	49.35%
Item 12:	IN

Cusip # G22944121
Item 1:	Reporting Person - Abigail P. Johnson
Item 4:	United States of America
Item 5:	0
Item 6:	0
Item 7:	345,845,160
Item 8:	0
Item 9:	345,845,160
Item 11:	49.35%
Item 12:	    IN


SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)

This Schedule 13G is filed solely to correct a clerical error contained in the
report filed for the year ended December 31, 2000.  This Schedule 13G contains
the Reporting Persons' beneficial ownership as of December 31, 2000.

Item 1(a).	Name of Issuer:

		COLT Telecom Group Plc

Item 1(b).	Name of Issuer's Principal Executive Offices:

		15 Marylebone Road
		London, NW15JD
		United Kingdom

Item 2(a).	Name of Person Filing:

		FMR Corp.

Item 2(b).	Address or Principal Business Office or, if None, Residence:

		82 Devonshire Street, Boston, Massachusetts  02109

Item 2(c).	Citizenship:

		Not applicable

Item 2(d).	Title of Class of Securities:

		Ordinary Shares

Item 2(e).	CUSIP Number:

		G22944121

Item 3.	This statement is filed pursuant to Rule 13d-1(b) or 13d-2(b) and the
person filing, FMR Corp., is a parent holding company in accordance with
Section 240.13d-1(b)(ii)(G).  (Note:  See Item 7).

Item 4.	Ownership

	(a)	Amount Beneficially Owned:	345,845,160

	(b)	Percent of Class:	49.35%

	(c)	Number of shares as to which such person has:

	(i)	sole power to vote or to direct the vote:	345,845,160

	(ii)	shared power to vote or to direct the vote:	0

	(iii)	sole power to dispose or to direct the disposition of:	345,845,160

	(iv) 	shared power to dispose or to direct the disposition of:	  0

Item 5.	Ownership of Five Percent or Less of a Class.

	Not applicable.

Item 6.	Ownership of More than Five Percent on Behalf of Another Person.

		Various persons beneficially own and have the right to
	receive or the power to direct the receipt of dividends from,
	or the proceeds from the sale of, the ordinary shares of COLT
	Telecom Group Plc.
		The interest of Colt, Inc. in the ordinary shares of
	COLT Telecom Group Plc amounted to 156,742,081 shares
	or 22.37% of the total ordinary shares deemed to be
	outstanding at December 31, 2000.
		The interest of Fidelity Investors Limited Partnership
	in the ordinary shares of COLT Telecom Group Plc amounted to
	131,049,559 shares or 18.70% of the total ordinary shares deemed
	to be outstanding at December 31, 2000.

Item 7.	Identification and Classification of the Subsidiary Which Acquired
the Security Being Reported on By the Parent Holding Company.

	See attached Exhibit(s) A, B, and C.

Item 8.	Identification and Classification of Members of the Group.

	Not Applicable. See attached Exhibit A.

Item 9.	Notice of Dissolution of Group.

	Not applicable.

Item 10.	Certification.

	Not applicable.

Signature

	After reasonable inquiry and to the best of my knowledge and belief,
	I certify that the information set forth in this Schedule 13G in
	connection with FMR Corp.'s beneficial ownership of the Ordinary
	Shares of COLT Telecom Group Plc at December 31, 2000 is true,
	complete and correct.

	October 10, 2001
Date


	/s/Eric D. Roiter
Signature


	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of FMR Corp. and its direct and indirect
	subsidiaries


				Exhibit A
SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)

		Colt, Inc. ("COLT"), 82 Devonshire Street, Boston,
	Massachusetts 02109, an indirect wholly-owned subsidiary of FMR Corp.,
	is the beneficial owner of 156,742,081 shares or 22.37% of the
	ordinary shares deemed to be outstanding of COLT Telecom Group Plc
	("the Company"). On September 27, 2001 COLT, Inc. transferred
	53,000,000 shares beneficially owned by COLT, Inc., or 7.56% of
	the ordinary shares deemed to be outstanding at December 31, 2000,
	to The COLT, Inc. 2001 Annuity Trust and 5,000,000 shares beneficially
	owned by COLT, Inc., or 0.71% of the ordinary shares deemed to be
	outstanding at December 31, 2000, to The COLT, Inc. 2001 Charitable
	Trust (together, the "COLT Trusts").  The Trustee of the COLT Trusts
	is Fidelity Management Trust Company, a direct wholly-owned subsidiary
	of FMR Corp.  Under the trust agreements for the COLT Trusts,
	COLT, Inc. has retained the sole power to direct the voting by the
	trustee of the shares held in the COLT Trusts.  Under the trust
	agreement for the The COLT, Inc. 2001 Annuity Trust, the trustee
	has agreed not to dispose of any of the shares held in the trust
	during the five-year term of the trust (other than in payment of
	the annuity amount).  During the five-year term of The COLT, Inc.
	2001 Charitable Trust, the trustee has the sole power to dispose of
	the shares held in the trust.

		Edward C. Johnson 3d, Chairman and Chief Executive Officer
	of FMR Corp., and FMR Corp., each may be deemed to have sole power to
	vote or direct the vote and to dispose of the 156,742,081 ordinary
	shares owned by COLT.

		Strategic Advisers, Inc., 82 Devonshire Street, Boston, MA
	02109, a wholly-owned subsidiary of FMR Corp. and an investment
	adviser registered under Section 203 of the Investment Advisers Act
	of 1940, provides investment advisory services to individuals.
	Strategic Advisers, Inc. has sole voting and dispositive power over
	29,913,045 shares or 4.27% of the ordinary shares deemed to be
	outstanding at December 31, 2000, beneficially owned through
	Strategic Advisers, Inc.

		Fidelity Investors Limited Partnership ("FILP"), 82
	Devonshire Street, Boston, Massachusetts 02109, a Delaware limited
	partnership, is the beneficial owner of 131,049,559 shares or 18.70%
	of the ordinary shares deemed to be outstanding at December 31, 2000
	of the Company.  Fidelity Investors Management, LLC ("FIML"), a
	Delaware limited liability company, is the general partner and
	investment manager of FILP, and is an investment manager registered
	under Section 203 of the Investment Advisers Act of 1940.  The members
	of FIML and the limited partners of FILP are certain shareholders and
	employees of FMR Corp.

		On October 3, 2001, COLT announced that it plans to raise
	approximately 400 million British pounds sterling (which is
	equivalent to approximately $587.7 million or 639.6 million euros)
	through an open offer on a pre-emptive basis to qualifying
	shareholders (the "Offering"). COLT also announced that COLT and
	FMR had entered into an open offer agreement (the "Agreement").
	Pursuant to the terms of the Agreement FMR has agreed, subject to
	certain conditions, to purchase its proportionate share in the
	Offering, to purchase the share of any other shareholder that
	declines to participate in the Offering and to purchase an additional
	number of shares, if any, that would give FMR a 54% ownership in COLT
	following the Offering.  FMR disclaims "beneficial ownership" of
	the securities that may be purchased by it pursuant to the Agreement
	because its purchase is currently subject to certain material
	conditions, including independent shareholder approval and regulatory
	approvals, that are not within its control.

		Members of the Edward C. Johnson 3d family are the predominant
	owners of Class B shares of common stock of FMR Corp., representing
	approximately 49% of the voting power of FMR Corp.  Mr. Johnson 3d
	owns 12.0% and Abigail Johnson owns 24.5% of the aggregate outstanding
	voting stock of FMR Corp.  Mr. Johnson 3d is Chairman of FMR Corp.
	and Abigail P. Johnson is a Director of FMR Corp.  The Johnson family
	group and all other Class B shareholders have entered into a
	shareholders' voting agreement under which all Class B shares will
	be voted in accordance with the majority vote of Class B shares.
	Accordingly, through their ownership of voting common stock and the
	execution of the shareholders' voting agreement, members of the Johnson
	family may be deemed, under the Investment Company Act of 1940, to
	form a controlling group with respect to FMR Corp.

		Fidelity International Limited, Pembroke Hall, 42 Crowlane,
	Hamilton, Bermuda, and various foreign-based subsidiaries provide
	investment advisory and management services to a number of non-U.S.
	investment companies and certain institutional investors.  Fidelity
	International Limited is the beneficial owner of 28,140,475 ordinary
	shares or 4.02% of the ordinary shares deemed to be outstanding at
	December 31, 2000 of the Company.  Additional information with respect
	to the beneficial ownership of Fidelity International Limited is shown
	on Exhibit B, page 9.


Exhibit B
SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)

		This Exhibit has been prepared  to identify Fidelity
	International Limited (FIL), Pembroke Hall, 42 Crow Lane, Hamilton,
	Bermuda, a Bermudan joint stock company incorporated for an unlimited
	duration by private act of the Bermuda Legislature and an investment
	adviser to various investment companies and certain institutional
	investors, as a beneficial owner of the 28,140,475 ordinary shares
	or 4.02% of the ordinary shares deemed to be outstanding at
	December 31, 2000 of the Company.

		Prior to June 30, 1980, FIL was a majority-owned subsidiary of
	Fidelity Management & Research Company (Fidelity), a wholly-owned
	subsidiary of FMR Corp.  On that date, the shares of FIL held by
	Fidelity were distributed, as a dividend,  to the shareholders of
	FMR Corp.  FIL currently operates as an entity independent of
	FMR Corp. and Fidelity.  The International Funds and FIL's other
	clients, with the exception of Fidelity and an affiliated company
	of Fidelity, are non-U.S. entities.

		A partnership controlled by Edward C. Johnson 3d and members
	of his family owns shares of FIL voting stock with the right to cast
	approximately 39.89% of the total votes which may be cast by all
	holders of FIL voting stock.  Mr. Johnson 3d is Chairman of FMR Corp.
	and FIL.  FMR Corp. and FIL are separate and independent corporate
	entities, and their Boards of Directors are generally composed of
	different individuals.  Other than when one serves as a sub adviser
	to the other, their investment decisions are made independently, and
	their clients are generally different organizations.

		FMR Corp. and FIL are of the view that they are not acting
	as a "group" for purposes of Section 13(d) under the Securities
	Exchange Act of 1934 (the "1934" Act) and that they are not otherwise
	required to attribute to each other the "beneficial ownership" of
	securities "beneficially owned" by the other corporation within the
	meaning of Rule 13d-3 promulgated under the 1934 Act.  Therefore,
	they are of the view that the shares held by the other corporation
	need not be aggregated for purposes of Section 13(d). However,
	FMR Corp. is making this filing on a voluntary basis as if all of
	the shares are beneficially owned by FMR Corp. and FIL on a
	joint basis.

		FIL does not have a present plan or proposal which relates
	to or would result in (i) an extraordinary corporate transaction,
	such as a merger, reorganization, liquidation, or sale or transfer
	of a material amount of assets involving the Company or any of its
	subsidiaries, (ii) any change in the Company's present Board of
	Directors or management, (iii) any material changes in the Company's
	present capitalization or dividend policy or any other material
	change in the Company's business or corporate structure, (iv) any
	change in the Company's charter or by-laws, or (v) the Company's
	common stock becoming eligible for termination of its registration
	pursuant to Section 12(g)(4) of the 1934 Act.







 .


Exhibit C
SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)
RULE 13d-1(f)(1)  AGREEMENT

		The undersigned persons, on October 10, 2001, agree and
	consent to the joint filing on their behalf of this Schedule 13G
	in connection with their beneficial ownership of the Ordinary Shares
	of COLT Telecom Group Plc at December 31, 2000.

FMR Corp.

By   /s/Eric D. Roiter
	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of FMR Corp. and its direct and indirect
	subsidiaries

Edward C. Johnson 3d

By   /s/Eric D. Roiter
	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of Edward C. Johnson 3d

Abigail P. Johnson

By   /s/Eric D. Roiter
	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of Abigail P. Johnson

Fidelity Management & Research Company

By   /s/Eric D. Roiter
	Eric D. Roiter
	Senior V.P. and General Counsel








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