Holding(s) in Company

1.

Identity of the issuer or the underlying issuer of existing shares to which voting rights are attached

PROTON POWER SYSTEMS PLC

2.

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

An acquisition or disposal of voting rights

(X)

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

( )

An event changing the breakdown of voting rights

( )

Other (specify):

( )

3.

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

Kaupthing Singer & Friedlander Ltd (in Administration)

4.

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

Kaupthing Singer & Friedlander Ltd (in Administration)

5.

Date of the transaction (and date on which the threshold is crossed or reached if different):

11.05.2009

6.

Date on which issuer notified:

12.05.2009

7.

Threshold(s) that is/are crossed or reached:

3%

8.

Notified details:

Sold 250,000

Class/type of shares (if possible using the ISIN code)

GB00B00QHC86

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

Direct

Direct

Indirect

Direct

Indirect

2,520,000

2,520,000

2,270,000

2,270,000

2.79%

Type of financial instrument

Expiration date

Exercise/Conversion Period/Date

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

% of voting rights

Number of voting rights

% of voting rights

2,270,000

2.79%

9.

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

Kaupthing, Singer & Friedlander Ltd (In Administration) is in administration. The Company was placed into administration pursuant to a court order made on 8 October 2008. Margaret Elizabeth Mills, Patrick Joseph Brazzill, Thomas Merchant Burton and Alan Robert Bloom were appointed joint administrators of the Company.

10.

Name of the proxy holder:

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:

Based on issue share capital of 81,390,863

14:

Contact name:

Elizabeth Hughes

15.

Contact telephone number:

0203 205 6624