Its July House Price Index found that sellers have suffered from miserable ‘viewing’ weather and “Olympic distractions.”

Rightmove said that the number of would-be sellers this month outnumbered successful buyers by two to one.

Miles Shipside, director of Rightmove, said: “Those who have been on the market for many months might consider the prospects of achieving a sale to be somewhat of an Olympian challenge given that actual sales completions are just half what they were five years ago. The weather might not be hot but in most parts of the country the competition to sell is.

“Those fit to buy this summer will be looking for a property that is prepared for sale better than the rest in terms of value and quality. There is evidence that quality remains in higher demand in spite of the downturn, and those keen to sell need to be clear on what it will take to make their property a compelling buy.”

The Index show that the monthly average run-rate of properties coming to market is just under double the level of completed sales.

Land Registry data for the last 12 complete months shows average sales completions running at 56,220 per month. Rightmove, which covers over 90% of the market, records a monthly average of new property listings over the same period of 102,121.