Value of my flat has fallen by 50 per cent

He purchased the property as an investment, hoping its value would soar so he could sell it for a profit within a year.

Instead he finds himself in a negative equity nightmare and has no idea how long he will be forced to hang on to the property for.

Mr Conroy, 43, from Chelsea, and his partner Caroline Faulkner bought the tiny 120sq ft flat for £175,000 in August last year.

They had it valued soon after and were told it could sell for £225,000. But a year later its value had fallen to as little as £80,000.

Mr Conroy said: "It's like being hit in the stomach. It's the biggest drop I've heard of, and I scan all the property news. A £95,000 drop that's 50 per cent."

He admitted he paid over the odds for the flat in a Regency stucco-fronted terrace in Winchester Street. Its original asking price was £150,000.

But at the time the property market appeared to be soaring and Mr Conroy was convinced it was a good investment.

The full-time property investor, who owns a string of buy-to-let flats, said he would rent it out. But if he cannot attract enough rent to cover the mortgage he will be in a serious financial trap.

Rents are falling by 20 per cent across the capital because of over-supply.

Thousands of owners who hoped to ride out the credit crunch with lucrative buy-to-let investments are being hit by the drop in rents.

The owner of one Chelsea house, which was let last year for £2,700 a week, was taking offers for £2,000 a year later.