One of Britain's best-known philanthropists has launched a strongly-worded attack on Lord Sadiq Khan’s transport policies - claiming they have driven to quit London and move to the United States.

Sir Peter Lampl, founder of the education charity the Sutton Trust, said he left Britain last year after concluding that it had become too difficult to move around the capital for his work and charitable commitments.

The businessman, who made his fortune in private equity before establishing the Sutton Trust in 1997, made the comments as he reflected on his decision to leave the UK, The Sunday Telegraph reports.

Sir Peter said the ability to travel quickly between meetings had been a key part of his work over several decades, both in business and in his campaigning efforts to improve social mobility.

Explaining his decision, he wrote that in the US “people who need to get about in cars are not treated entirely as pariahs”.

He went on: ”More and more people of my type appear to have come to the same conclusion... It’s a mass exodus.

“And while there will be many other reasons that so many other wealthy individuals have quit Britain, for me not being able to move around the city as I needed to was the clinching factor.”

The philanthropist argued that changes to London's road network, including the growth of cycle infrastructure, low-traffic neighbourhoods and wider 20mph limits, had made journeys across the capital more challenging.

Sir Peter, who stepped down as executive chairman of the Sutton Trust in 2024 after donating more than £65 million to the organisation, said the issue had become increasingly significant in recent years.

He added the changing nature of travel in the capital ultimately persuaded him that he wanted to live elsewhere, concluding: "In short, I needed a different kind of London."

His comments come amid a fierce debate over the impact of transport and traffic policies introduced in London under Mayor Lord Khan.

Supporters argue the measures have improved road safety, encouraged more people to walk and cycle, and helped tackle pollution, while critics contend they have increased congestion and made some journeys slower.

Traffic data company TomTom has previously ranked London among the world's slowest-moving cities for drivers, with central London journey times affected by a range of factors including roadworks, traffic levels, street design and speed restrictions.

Responding to his comments, Transport for London said its own figures showed journey times on its road network remained broadly similar to those recorded in 2019.

A TfL spokesman said its recently launched "London on the Move" plan was designed to cut congestion and highlighted that black cabs can use most bus lanes across the capital. The organisation also said the congestion charge had proved effective at reducing traffic levels.

The spokesman added: "We continue to make London's world-class public transport, walking and cycling offer better than ever to ensure people can get to where they need to be affordably and sustainably."