London mayor Boris Johnson’s chief of staff, Sir Simon Milton, died this week aged 49 from leukaemia-related illness

Sir Simon, who passed away on Monday at a London hospital, was deputy mayor and mayor for policy and planning.

Johnson paid this tribute to Milton: “He was a wonderful colleague and friend, and will be much missed by everyone who was involved in public life in this city.”

Milton was knighted for services to local government in the New Year’s Honours list in January 2006, following a career at Westminster City Council, of which he became leader in 2000.

In 2007 he was elected chairman of the Local Government Association and was appointed deputy mayor of the Greater London Authority in September 2008.

He supported the mayor on strategic planning applications, while focusing on GLA budgets and administration. Johnson added: “He was kind, decent, and he was universally acknowledged to be brilliant at his job.

He was a widely admired leader of Westminster council, who played a key role in launching the first academy schools. He brought the same calm, logic and warmth to his role at City Hall.

It is a great shock that he has been taken from us when he had so much still to offer.”