Yeah the only way that could happen is if someone has withdrawn a bid, But it doesn't just withdraw 1 bid, say someone has set their maximum bid to say £2000, and the he withdraws that bid, it withdraws every bid they have made to get to where the bidding was when they withdrew, so that takes the bid down quite a lot as in this case. I bet the seller is p***ed off tho'. Complicated I know, but that's how it works. Then maybe the same bidder that withdrew their bid has placed a smaller bid?
Just looked again and these are the withdrawn bids
Bid retraction and cancellation history
Bidder
Action
Date of bid and retraction
p***i( 112)
Retracted: £1,550.00
Bid:30-Mar-15 21:41:54 BST Retracted: 04-Apr-15 20:33:22 BST
2***l( 739)
Retracted: £1,020.00
Bid:28-Mar-15 19:27:02 GMT Retracted: 04-Apr-15 20:58:34 BST
.***0( 16)
Retracted: £1,600.00
Bid:31-Mar-15 19:36:42 BST Retracted: 04-Apr-15 18:38:55 BST
Strange that, 3 different bidders retracting bids?? They may have been reading this thread, or apparently another one has gone on for £1200 so I have been made aware.