It is signed by Mayor Biggs along with Helel Abbas, the last council leader before a referendum in 2010 led to Tower Hamlets first election for an executive mayor that year - which Mr Rahman won in a landslide.
Others signing include mayoral candidates in previous years the Conservatives Peter Golds, Anwara Ali and Chris Wilford; the Greens’ Tim Kierly; and the Lib Dems’ Elaine Bagshawe, John Griffiths and a former supporter of Mr Rahman, Rabina Khan, who later ran as a candidate for the People’s Alliance.
Lutfur Rahman and Ken Livingstone drumming up support in Roman Road Market on campaign trail for mayor in 2010