That bidder may be unaware that the minimum Reserve price you can set is £50.00 (costs 4% fee on price set - sold or not ... starting at £49.50 or less would have meant no fee) and is increasing bid amounts in trying to find that reserve price.
'Bid stacking' ploy is also used by some in attempts to discourage others from bidding against the multiple bid numbers showing. Bid amount will not increase until a different ID bidder places a bid on the item.
