The May survey from the property body RICS once again points to house price falls - not deep, but widely spread. But the real threat claim its economists is from a freezing up of the market.

Official figures point to a drop of about a quarter in the level of transactions in the first four months of this year compared with the average last year. But the RICS survey suggests that the level of sales is set to drop further.

The average number of transactions per surveyor (over the last three months) is now at 17.4, the lowest figure since 1978 and the net balance of new agreed sales remains in negative territory, says RICS.

Bad news for estate agents, but this is also very worrying for small builders, along with companies that get a boost in sales from house movers.

The RICS sees one glimmer of hope, that there has been no flood of distressed sales. There has been if anything less property coming onto the market. However, the tone suggests that this problem sits like a dam everyone fears may burst. If it does the picture of relatively contained falls in house prices will change radiply and the consequences worsen for both home sellers, house builders and the wider economy.