Roger Evans, Havering’s representative in the London Assembly for 15 years, will call time on his political career in May.
The Conservative, who has represented Havering and neighbouring borough Redbridge since the formation of the assembly in 2000, will not stand in next year’s election.
Instead he plans to set out on a “busman’s” holiday exploring the world’s other great cities, including Hong Kong, Rio de Janeiro and New York.
Explaining his decision this week Mr Evans said: “I will have been doing this job for 16 years – so here at the assembly since the beginning.
“This year I’m deputy mayor and last year chairman of the assembly, the two biggest jobs I can do, so there’s nothing really left to do here.
“If I came back after the election I would just be a backbencher.”
The politician, who became deputy mayor in May after predecessor Victoria Borwick stood down, said his key success was campaigning for outer London.
“I really have seen my role as making the voice of outer London, particularly Havering and Redbridge, clear at City Hall.
“There’s a tendency just to look at central London where all the people with influence are and it’s easy for government to overlook outer London.
“I’m pleased to have defended it during the Livingstone years and pleased Boris’ administration has focused on outer London.”
Mr Evans said he was also pleased to have secured disabled access at all Crossrail stations through Havering and Redbridge and to have largely defended emergency services in the two boroughs from cuts.
The exception was Wanstead police station, which closed in 2013, following what Mr Evans called a “tough battle”.
In his final eight months at the assembly he said would push Mayor of London, Boris Johnson, for more improvements at Romford and Ilford stations where he sees “a real opportunity”.
Despite successes Mr Evans said he was disappointed not to have seen problems on the A12 resolved, particularly at Gallows Corner, Romford, and Redbridge roundabout, but was confident that both were on course to be improved.
Following his trip Mr Evans said he will coach people in public speaking and help women entering politics.
He added that although he has no plans to return to politics after May 2016 he suspects he will “keep a toe in the water”.
The Conservative candidate to bid to represent the two boroughs will be selected in September.
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