Retrospective VAT claim on mileage

Hi

I think the answer to this is probably no, but wanted to check whether anyone else had tried...

A client has never claimed for the VAT element on his mileage claim and, as he does approx 20,000 business miles a year (he does keep a log of where he has been)if I can go back 4 years and claim the VAT it would be c£1500 so would be worth doing.

However, I know you are supposed to have supporting VAT receipts but wondered whether anyone had successfully managed to put through a claim for the VAT on mileage for the last few years without any receipts (as I am guessing that he hasnt kept all his petrol receipts). I know we will be ok going forward as I can get him to keep them from now on.

Any answers would be most appreciated