Dialight Regulatory News (DIA)

TR-1: NOTIFICATION OF MAJOR INTERESTS IN SHARES

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

Dialight Plc

2. Reason for the notification:

An acquisition or disposal of voting rights

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

BT Pensions Scheme Trustees Limited as trustee of the BT Pension Scheme.

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

Hermes UK Specialist Focus Fund

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

11TH March 2010

6. Date on which issuer notified:

12th March 2010

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

Crossed from 9% to 6%

8. Notified details:

A: Voting rights attached to shares

B: Financial Instruments

Total (A+B)

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

BT Pension Scheme Trustees Limited, as trustee of the BT Pension Scheme ("BTPS") is the parent undertaking of Britel Fund Nominees Limited and Britel Fund Trustees Limited, which is the parent undertaking of Hermes Fund Managers Limited ("HFML"). HFML is the parent undertaking of:

1. Hermes Equity Ownership Services Limited ("HEOS") (voting rights: 0.148%)*

2. Hermes Focus Asset Management Limited ("HFAM")** as General Partner of the following limited partnerships:

a. Hermes UK Specialist Focus Fund ("HUKSFF") (voting rights: 6.598%) ***

* This notification is also being made in respect of HEOS, which is an indirect holder of shares for the purpose of DTR 5.2.1(h). The voting rights include the following: (i) all of the voting rights of the underlying clients of HEOS for whom it provides voting services; (ii) all of the voting rights attaching to the direct shareholding of BTPS; (iii) all of the voting rights attaching to shares managed by HIML; and (iv) the voting rights attaching to the direct shareholding of BTPS that are managed by HSL.

** This notification is also being made in respect of HFAM, which is an indirect holder of shares for the purpose of DTR 5.2.1(h) and has an individual notification obligation under DTR 5.1.5

*** This notification is also being made in respect of HUKSFF, which has an individual notification obligation under DTR 5.1.

Please see Section 13 for further information.

10. Name of the proxy holder:

See Comment in Section 13

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

See Comment in Section 13

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

See Comment in Section 13.

13. Additional information:

HEOS hold the voting rights under a standing proxy contained in agreements for the provision of voting services to various underlying clients for the purposes of DTR 5.2.1.(h), which includes all the shares owned directly by BTPS, all of the voting rights attaching to shares managed by HIML and the voting rights attaching to the direct shareholding of BTPS that are managed by HSL.

HFAM hold the voting rights as General Partner under a standing proxy contained in limited partnership agreements with various limited partnerships for the purposes of DTR 5.2.1(h).

All voting rights held on behalf of the above entities are aggregated for the purposes of DTR 5.2.1(e).

This disclosure is made by BT Pension Scheme Trustees Limited as trustee of the BT Pension Scheme, which is the ultimate parent undertaking for the purposes of DTR 5.2.1(e).

14. Contact name:

Hermes - Valerie Davidson (v.davidson@hermes.co.uk) 020 7680 2177 or Margaret Moss (m.moss@hermes.co.uk) 0207 680 2125

Dialight plc - Nick Giles 01480 447491

Date: 15 March 2010