The survey has the advantage that it independent and rooted in reality, but it is not scientific in any way. At Sandfords we are particularly aware of one of its big deficiencies – in the exclusive market where we operate, vendors very rarely allow us to put up signs at all, so the number of sales we have been making would have been grossly underestimated by the men in vans who manage them.

In fact, in many cases we have sold properties before they are even advertised, so the sale goes unrecorded until the Land Registry survey picks them up. By then, of course, they are of largely historic interest.

Central London estate agents as a whole are agreed that supply is so tight and demand so consistent that prices are being maintained at the top end. Buyers who waited for prices to come down last year have missed properties they liked, and may now have to pay more.