Inmarsat Regulatory News (ISAT)

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARESi

1. Identity of the issuer or the underlying issuer of existing shares to which voting rights are attached: ii

Inmarsat Plc

Sedol B09LSH6

2 Reason for the notification (please tick the appropriate box or boxes):

An acquisition or disposal of voting rights

√

An acquisition or disposal of qualifying financial instruments which may result in the acquisition of shares already issued to which voting rights are attached

An acquisition or disposal of instruments with similar economic effect to qualifying financial instruments

An event changing the breakdown of voting rights

Other (please specify):

3. Full name of person(s) subject to the notification obligation: iii

¹Lansdowne Partners Limited being the General Partner of Lansdowne Partners Limited Partnership

²Lansdowne Partners International Limited

4. Full name of shareholder(s)  (if different from 3.):iv

Morstan Nominees Ltd &

HSBC Client Holdings UK Ltd

Vidacos Nominees Ltd

(Registered Shareholders)

5. Date of the transaction and date on which the threshold is crossed or reached: v

07/10/2010

6. Date on which issuer notified:

08/10/2010

7. Threshold(s) that is/are crossed or reached: vi, vii

14%

8. Notified details:

A: Voting rights attached to shares viii, ix

Class/type of shares

if possible using the ISIN CODE

Situation previous to the triggering transaction

Resulting situation after the triggering transaction

Number of Shares

Number of Voting Rights

Number of shares

Number of voting rights

% of voting rights x

Direct

Direct xi

Indirect xii

Direct

Indirect

Ordinary Shares

59,942,059

59,942,059

60,042,059

13.04%

GB00B09LSH68

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial instrument

Expiration date xiii

Exercise/ Conversion Period xiv

Number of voting rights that may be acquired if the instrument is exercised/ converted.

% of voting rights

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments xv, xvi

Resulting situation after the triggering transaction

Type of financial instrument

Exercise price

Expiration date xvii

Exercise/ Conversion period xviii

Number of voting rights instrument refers to

% of voting rights xix, xx

CFD

N/A

N/A

N/A

4,444,922

Nominal

Delta

0.97%

Total (A+B+C)

Number of voting rights

Percentage of voting rights

64,486,981

14.00%

9. Chain of controlled undertakings through which the voting rights and/or the financial instruments are effectively held, if applicable: xxi

Lansdowne Partners International Limited is the parent undertaking of Lansdowne Partners Limited.

Proxy Voting:

10. Name of the proxy holder:

Lansdowne Partners Limited

11. Number of voting rights proxy holder will cease to hold:

12. Date on which proxy holder will cease to hold voting rights:

13. Additional information:

14. Contact name:

Johanna Stohr

15. Contact telephone number:

+44(0)20 7290 5500