I guess the London effect has always been there, it just seems very strong at the moment.
Its not necessarily that people can't afford the next house, peole move downwards and sideways as well as upwards, there is just a dreadful shortage of decent houses coming on to the market combined with very strong demand, the perfect recipe to drive up prices, and the prices have gone up very rapidly in the last 2-3 months some properties are even exceeding peak autumn 2007 levels which i find completley astounding.
The attitude is that if a purchaser is lost no problem re-market and go for a higher price which has happened on 3 or 4 properties.