Annual Investment Allowance and first year of trading as sole trader

(I am assuming that the AIA is 100K, and that it has not change by the time you read this)

Assume a sole trader started trading on 5st Sep 2010, and he then spend 100K on capital plant.  As I understand it, the sole trader will be tax on a period of 5st Set 2010 to 5 Apr 2011, so will only get half of the AIA. This means that 50K of the capital investment will not be covered by the AIA.  This does not seem very far because:

• If the person started trading on the 5th Apr 2010, he would get a full AIA of 100K,
• Likewise if the person was trading var a LTD he would get a full AIA, as his companies tax year would be 12 months long.

Can the AIA be used in the next tax year to cover the other 50K of investment?  Does the accountancy date of the sole trader effect this in any way?  What am I missing…  (Please make clear if your answer is posted after the 22 June, if it takes into account any changes to the rules…)