He has sold the world’s most expensive house and rubbed shoulders with the political elite – but life was not always so glamorous for the keeper of keys to Billionaires’ Row.

His office on the edge of Hampstead Garden Suburb, adorned with letters from prime ministers and press cuttings from national newspapers, is a far cry from the shabby hotel room in Golders Green where Trevor Abrahmsohn forged his reputation as estate agent to the globe’s glitterati.

Armed with nothing but a temperamental phone line and a photocopier, the 58-year-old went on to enjoy 35 years selling “trophy mansions” on The Bishops Avenue to Saudi princes, Chinese businessman and Russian oligarchs.

“The economic climate in 2008 was a walk in the park compared to the depression of 1974,” said Mr Abrahmsohn, owner of Glentree Estates. “It was on a different scale, an awful time to do business, but I said to myself: ‘Big properties have big commissions and colourful characters sell them.’

“So I just wrote to all the wealthiest people in the area saying I’m going to do something for you that you have never heard of before.”

Born to a family of medical practitioners, Mr Abrahmsohn gave up on his degree in dentistry to take a punt on life in the “intoxicating” world of property.

Targeting Hampstead and Highgate’s richest residents, he claims to have reinvented the role of the estate agent from “Dickensian valuers” to “marketing specialists”.

The former Quintin School (now Quintin Kynaston in St John’s Wood) pupil has certainly cornered the market on the capital’s most infamous stretch of real estate, The Bishops Avenue, claiming to have secured almost 95 per cent of sales over 35 years. He has sold homes belonging to murdered Greek businessman Aristos Constantinou – the home was still riddled with bullet holes – actress Gracie Fields and the recently jailed tycoon Asil Nadir.

Although the owners of the mansions which line the sweeping boulevard have changed, the road’s stardust has not diminished.

The �100million Heath Hall went on the market last month, with the brochure costing �2,000.

Mr Abrahmsohn said: “In the 1920s The Bishops Avenue was the place where the British captains of industry and diplomats used to reside and why? Because they could have a country house and a town house in one place.

“But in the ’70s London changed from a souvenir city to the greatest city in the world and people bought property here whether they needed it or not.

“When Saddam Hussein marched into Kuwait, the Saudi Royal family bought 15 properties in and around The Bishops Avenue to house the expelled members should Hussein have gone further.”

Mr Abrahmsohn claims there is no ceiling to the spiralling house prices in the area, which has attracted the likes of media mogul Richard Desmond.

“As Mark Twain said: ‘Buy land, they’re not making it any more’,” he added.