Diploma Regulatory News (DPLM)

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARES

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

Diploma Plc

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

An acquisition or disposal of voting rights

ü

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:

FMR LLC

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

See attached schedule

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

20 May 2010

6. Date on which issuer notified:

24 May 2010

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

10%

8. Notified details:

A: Voting rights attached to shares

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

Direct

Direct

Indirect

Direct

Indirect

GB0001826634

11,549,668

11,549,668

11,066,718

11,066,718

 9.77

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial instrument

Expiration date

Exercise/ Conversion Period

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

Resulting situation after the triggering transaction

Type of financial instrument

Exercise price

Expiration date

Exercise/ Conversion period

Number of voting rights instrument refers to

% of voting rights

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

11,066,718

9.77

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

See attached schedule

Proxy Voting:

10. Name of the proxy holder:

FMR LLC

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

482,950

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

20 May 2010

13. Additional information:

None

14. Contact name:

Shaheen Hussain

15. Contact telephone number:

fil-regreporting@fil.com

FMR

Issuer name:

 DIPLOMA PLC

Current ownership percentage:

9.77%

Total shares held:

 11,066,718

Issued share capital:

 113,239,555

SHARES HELD

NOMINEE

MANAGEMENT COMPANY

FMR LLC is the parent holding company of Fidelity Management & Research Company (FMRCO) Investment Manager for US mutal Funds and FIL Management Trust

Company (FMTC) and Pyramid Global Advisors Trust Company (PGATC), a US Chartered Bank which acts as a trustee or Investment Manager of various pension and trust accounts

and Pyramid Global Advisors LLC (PGALLC)

379,850

BROWN BROTHERS HARRIMAN AND CO

FMRCO

30,200

BROWN BROTHERS HARRIMAN AND CO

PTC

362,700

MELLON BANK N.A.

FMRCO

188,871

MELLON BANK N.A.

PTC

123,600

NORTHERN TRUST CO

FMRCO

2,050,000

STATE STREET BANK AND TR CO

FMR

7,495,967

STATE STREET BANK AND TR CO

FMRCO

68,300

STATE STREET BANK AND TR CO

PTC

198,924

STATE STREET BANK AND TR CO

PGATC

97,806

CIBC MELLON TRUST (C)

FCL

70,400

MELLON BANK NA (C)

PTC