The buoyancy in the market is masking real dangers for the economy and for families

Liz Potter National Housing Federation

This figure puts the price of homes in rural areas such as North Yorkshire, as well as the more affluent south eastern counties, beyond the reach of all but the top-earning 30% of UK households.

The survey comes amid growing fears of overheating in the UK housing market, with the Royal Institution of Chartered Surveyors (RICS) on Tuesday becoming the latest group to warn of a slowdown.

"Many chartered surveyors are reporting a levelling off in prices, some even a downturn in inquiries," RICS national housing spokesman Ian Perry said.

"There are real signs coming from the marketplace that the housing boom may have reached its peak."

Regional data

The NHF survey, based on Land Registry figures published two weeks ago, reflects findings that Kensington & Chelsea is the UK's most expensive area to live in.

Homebuyers needing earnings of �179,851 a year to support a mortgage large enough to buy an average home in the London borough.

In only one London borough, Barking and Dagenham, can the average UK household income of �29,640 buy a home.

Outside the capital, earnings of �52,000 a year are needed to afford the average home in Hertfordshire and Oxfordshire, with almost �31,000 required to buy a home in Cornwall, considered one of the UK's least affluent counties.

Less expensive areas for buying a home include Hull, where a salary of �13,000 would support a mortgage sufficient to buy the average home, Middlesbrough, where �15,200 is needed, and North East Lincolnshire, where �16,500 is required.

Key workers

The NHF, which has based its analysis on a 95% mortgage awarded at three times annual income, warned that the rise underlined fears over the problems many "essential" workers, such as nurses and teachers, have in meeting accommodation bills.

"The high cost of housing is putting our essential services at risk - not just in the capital but now across many areas of the country," policy director Liz Potter said.

"The current buoyancy in the market is masking real dangers for the economy and for homes and families."

Police 'moonlighting'

Many police officers, especially around the Thames valley area, are working on days off to gain sufficient earnings to afford homes, the Police Federation said.

"We get officers moonlighting, taking on jobs such as driving, in order to meet mortgage payments," a federation spokesman told BBC News Online.

Nurses, who can expect to earn �18,310 a year after four years in the job, are working overtime, or in private clinics, to support living costs, the Royal College of Nursing said,

"We are very concerned about this issue," an RCN spokeswoman told BBC News Online.

"Some nurses only survive because friends offer them rooms free."

While the NHF welcomed the government's 'starter pack' initiative, which offers key workers average grants of �25,000 towards the cost of buying a home, it warned that the package will provide only limited relief from the affordable housing squeeze.

Prices to stagnate

But the Royal Institution of Chartered Surveyors warned that while house prices continued to increase between May and July, the rate of growth is likely to fall back as fears of redundancy grow.

"Recession in manufacturing is a fact and the service sector shows signs of following," Mr Perry said.

"The high prices coupled with fears of unemployment are certain to make many potential customers think again in the coming weeks."

The proportion of chartered surveyors expecting house prices to rise more than halved to 14% last month, compared with June's figure.

The RICS comments follow reports from lenders such as the Nationwide Building Society, and think-tanks including Cambridge Econometrics, that growth in house prices is set to slow.