It'll be the buyer protection fee if the seller was a private seller. When you place a bid, that amount includes the BPF. Then, at the end of the auction, the winning bid display shows what the seller actually receives so is really the highest bid minus the BPF. Your £42.00 minus the BPF will have been less than £40.71. Effectively, the winning bidder will actually have placed a bid higher than your £42.00 before ebay deducted the BPF. It's just ebay's cackhanded way of displaying it. It keeps catching people - unsurprisingly.