Henderson Group - Holding(s) in Company - AMP

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

Henderson Group 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 (please specify):

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

AMP Limited, AMP Life Limited and AMP Capital Investors Limited

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

Stichting Pensionfonds Hoogovens, Stichting Pensionfonds ABP, Government Employees Superannuation Board, QLD Local Government Superannuation Board and Commonwealth Bank Officers Superannuation Corporation Pty Limited as trustee for the Officers' Superannuation Fund.

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

27 September 2010

6. Date on which issuer notified:

29 September 2010

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

4% (crossing above 4%)

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 Voting Rights

Number of shares

Number of voting rights

% of voting rights

Direct

Indirect

Direct

Indirect

Ordinary shares (via CHESS Depositary Interests)

32,562,450

32,562,450

36,354,291

26,497,907

9,856,384

3.21%

1.19%

B: Financial Instruments

Resulting situation after the triggering transaction

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

Total (A+B)

Number of voting rights

% of voting rights

36,354,291

4.40%

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

AMP Life Limited is an indirect wholly owned subsidiary of AMP Limited.

AMP Capital Investors Limited is an indirect wholly owned subsidiary of AMP Limited.

Proxy Voting:

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:

Level 24, AMP Sydney Cove Building 33 Alfred Street Sydney New South Wales 2000

Fax: +61 2 9257 1541

14. Contact name:

James Crook, Senior Legal Counsel, AMP Capital Investors Limited

15. Contact telephone number:

+61 2 9257 1512