Sir Simon Milton’s career in local politics led him to one of the most powerful positions in the country. As deputy mayor of London, working alongside Boris Johnson (pictured with Sir Simon), he was regarded by many as the man “really running London”.

But it was his commitment to education, and particularly his pivotal role in establishing some of the first academy schools in the country, that defined his work in the political sphere.

Born in north-west London in the early 1960s, Sir Simon was the son of a German-Jewish emigre father who was sent to Britain just before the Second World War as part of the Kindertransport rescue mission.

He grew up in Cricklewood and attended the independent boys’ school St Paul’s in Hammersmith. Having excelled at school, he went on to read history at Gonville and Caius College, Cambridge.

It was here that Sir Simon’s interest in politics took hold. He was chairman of the Cambridge University Conservative Association and president of the Cambridge Union.

After completing a master’s degree at Cornell University in New York, and a stint working at Sharaton’s, his father’s chain of patisseries in London, Sir Simon finally entered politics after being elected to Westminster City Council in 1988.

Within three years he was deputy leader of the council, and it was here that his work in education began to take root.

By the time he had become its leader in 2000, Westminster was lingering at the foot of education league tables. In response, he introduced his One City strategy, which invested #163;1 million in improving secondary schools in the borough.

Sir Simon readily embraced Labour’s academy programme and used the initiative to arrest the decline of Westminster’s state schools.

Despite significant opposition, he closed North Westminster Community School and created the new Westminster Academy and Paddington Academy.

But it was in closing Pimlico Comprehensive that Sir Simon came into his own. Described by Nickie Aiken, now Westminster’s cabinet member for children, as a “dirty fight” between the council and the NUT, the school was eventually placed in special measures, enabling Sir Simon to take action and turn it into a high-performing academy.

In 2006 he was knighted for his services to local government, and in 2007 he married his partner and fellow Westminster councillor Robert Davis in a civil partnership.

In the same year, Sir Simon was made chair of the Local Government Association (LGA), where he became an outspoken advocate for academies and free schools, calling for more choice to be built into the system. He even called for private companies to be allowed to run the schools for a profit and suggested schools could “sweat” the most from their assets by hiring out their facilities during holidays.

His legacy in education is visible today, and it led to a jump in the performance of Westminster’s secondaries from just 40 per cent of its 16-year-olds leaving school with five good GCSEs in 2006 to 62.5 per cent last year.

Sir Simon was described as a “gentle and unassuming” man who was not just intelligent, but also a “brilliant political strategist, who always, instinctively, knew what to do”.

He had suffered poor health for a number of years. He was diagnosed with leukaemia in 1990, and underwent a bone-marrow transplant that used cells donated by his sister, Lisa. He later caught pneumonia while recovering, severely damaging his lungs.

Sir Simon died after a short illness on 11 April at the age of just 49.