| Group and Company | Total £m |
| Cost | |
| At 1 April 2006 | 2.4 |
| Disposals | (0.1) |
| At 31 March 2007 | 2.3 |
| Amounts written off/waived | (0.3) |
| At 31 March 2008 | 2.0 |
| Provision for impairment | |
| At 1 April 2006 and 31 March 2007 | 0.3 |
| Amounts written off/waived | (0.3) |
| At 31 March 2008 | – |
| Net book value at 31 March 2008 | 2.0 |
| Net book value at 31 March 2007 | 2.0 |
Available for sale financial assets as at 31 March 2008 and 31 March 2007 comprise unlisted, sterling-denominated securities held by AEA Technology plc. The Group holds these investments in entities where the Group has previously entered into corporate joint venture arrangements and they offer the Group the opportunity for return through dividend income.
Available for sale financial assets are held at fair value.
Available for sale financial assets include the following:
| 2008 £m |
2007 £m |
||
| Unlisted securities: | |||
| equity securities – United Kingdom | 2.0 | 2.0 | |
| 2.0 | 2.0 |