The Modern Method of Auction is different to traditional auction procedures in the UK, in that it is conditional. This means that the sale is not legally binding once a bid is accepted.
The successful bidder is required to pay a Buyers Reservation Fee/Deposit and sign a Reservation Agreement. The property is then reserved to the buyer. The buyer and seller are then required to unconditionally exchange contracts and complete the transaction within 56 days.
One of the positives with this method is that it opens the auction process up to those requiring lending due to the extended period between completion. See below pdf.Seller Guide