Director/PDMR Shareholding

DIPLOMA PLC

12 CHARTERHOUSE SQUARE, LONDON EC1M 6AX

TELEPHONE: +44 (0)20 7549 5700

FACSIMILE: +44 (0)20 7549 5715

FOR IMMEDIATE RELEASE

18 May 2010

DIPLOMA PLC - DIRECTORS' INTERESTS IN SHARES

Diploma PLC has been notified today that Mr JL Rennocks, the Chairman of the Company, has disposed of 150,000 ordinary shares of the Company at an average price of 236.7 pence per share. The Chairman retains 73,766 ordinary shares in the Company.

For further enquiries please contact:

Nigel Lingwood, Group Finance Director 020 7549 5705