You hear a lot about ‘sealed bids’ in prime central London. When competition is hot between buyers, they are invited to put forward their best and final offers for the property. Many people believe it gets the best deal for the vendor, and it offers a decisive answer for the would-be buyers.

Problem is, there are a lot of dangers inherent in sealed bids. We recently had a two-bedroom flat for sale in a prestigious block in Belgravia. Three parties wanted to buy t