Thanks for your reply. Indeed I now have realised that I've paid with my credit card, and still have the statements. So, that should be good as a proof.
Time to put together my things for tax return, and I realise that I have lost several travel receipts. I usually hold a monthly travelcard to get around for business, but receipts are missing for a few months.
Is there any way I can include these expenses wihtout an original receipt?