Capital Gains on US Home sale?

I am a UK national currently living in California on a green card.  After 20 years in the US I am planning on returning to the UK full time.  I would like to know if anyone can advise me on whether the capital gain from my house sale will be taxed by UK inland revenue?  I was hoping to complete the sale in the 2009/2010 tax year (i.e. prior to April 5th 2010) but that isn't going to happen now and the sale won't close until after the new UK tax year starts.  It is my primary residence, in fact the only home I own.   If it makes any difference  I will be using all proceeds (and probably more) to purchase a property in the UK.

regards
roman

You might want to check the british expats forum.  I know I found answers to this question on there last year - I think they related to Canada. 
http://britishexpats.com/forum/

My thinking was that this would be a better site to ask the question since it involves a home being sold in the US and was more likely to be read by someone who has been through a similar process.  So many of the rules relating to commonwealth countries are different to non-commonwealth countries.

Perhaps this will help you:
http://www.shelteroffshore.com/index.php/property/more/capital-gains-tax-rules-overseas-property-10295/

My understanding is that the UK has an exemption for your home just like the US (as in you wouldn't have to pay tax on the gains made from the sale of your primary residence as long as you pay it to another property).  I don't think that it matters whether it's in one tax year or another. 

http://www.direct.gov.uk/en/MoneyTaxAndBenefits/Taxes/TaxOnPropertyAndRentalIncome/DG_4016337

BUT - in your case I would be careful about when you return to the UK - as the answer could turn on your country of residence at the time of the sale, not just what tax year it falls into.

Good luck!