Rule 8.3 - LSE plc

Halcyon Asset Management LLC
                  



FORM 8.3

DEALINGS BY PERSONS WITH INTERESTS IN SECURITIES REPRESENTING 1% OR MORE

(Rule 8.3 of the City Code on Takeovers and Mergers)

1. KEY INFORMATION

Name of person dealing  (Note 1)          Halcyon Asset Management LLC and Halcyon Offshore Asset
                                           Management LLC on behalf of discretionary clients
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Company dealt in                          London Stock Exchange plc
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Class of relevant security to which the   Ordinary Shares
 dealings being disclosed relate (Note 2)
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Date of dealing                           May 2, 2006
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2. INTERESTS, SHORT POSITIONS AND RIGHTS TO SUBSCRIBE

(a) Interests and short positions (following dealing) in the class of relevant
security dealt in (Note 3)
                                          Long                          Short
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                                          Number                        Number
                                                       (%)                             (%)
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(1) Relevant securities
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(2) Derivatives (other than options)      5,977,151 2.3327%%
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(3) Options and agreements to
 purchase/sell
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Total                                     5,499,073 2.3327%
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(b) Interests and short positions in relevant securities of the company, other
than the class dealt in (Note 3)
       Class of relevant security:                     Long                          Short
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                                          Number                        Number
                                                       (%)                             (%)
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(1) Relevant securities
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(2) Derivatives (other than options)
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(3) Options and agreements to
 purchase/sell
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Total
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(c) Rights to subscribe (Note 3)

Class of relevant security:               Details
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3. DEALINGS (Note 4)

(a) Purchases and sales

Purchase/sale                      Number of securities              Price per unit (Note 5)
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(b) Derivatives transactions (other than options)

Product name,       Long/short (Note 6)    Number of securities (Note 7)   Price per unit (Note 5)
e.g. CFD
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CFD                 Long                   172,780 shares                  121595 GBp
CFD                 Long                   305,299 shares                  121981 GBp
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(c) Options transactions in respect of existing securities

(i) Writing, selling, purchasing or varying

Product name,      Writing,        Number of          Exercise  Type, e.g.   Expiry    Option money
e.g. call option    selling,        securities to     price      American,   date      paid/received
                    purchasing,     which the option             European               per unit (Note
                    varying etc.    relates (Note 7)             etc.                   5)
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(ii) Exercising

Product name, e.g. call option     Number of securities              Exercise price per unit (Note 5)
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(d) Other dealings (including new securities) (Note 4)

Nature of transaction (Note 8)     Details                           Price per unit (if applicable) (Note
                                                                      5)
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4. OTHER INFORMATION

Agreements, arrangements or understandings relating to options or derivatives

Full details of any agreement, arrangement or understanding between the person disclosing and any other
 person relating to the voting rights of any relevant securities under any option referred to on this
 form or relating to the voting rights or future acquisition or disposal of any relevant securities to
 which any derivative referred to on this form is referenced.  If none, this should be stated.
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Is a Supplemental Form 8 attached? (Note 9) NO

Date of disclosure                                          May 3, 2006
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Contact name                                                James W. Sykes
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Telephone number                                            212/303-9406
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If a connected EFM, name of offeree/offeror with which
 connected
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If a connected EFM, state nature of connection (Note 10)
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Notes

The Notes on Form 8.3 can be viewed on the Takeover Panel's website at
www.thetakeoverpanel.org.uk