The letter said: “Of course there are antisemitic comments made in the Labour Party. This should be rooted out and there should be no tolerance of it when it happens.
"However this is no different nor more frequent than in wider society and upon inspection, they come from both the left and right."
Cllr Bull allegedly made the "Shylock" comment about Cllr Brabazon at a Council Cabinet meeting in July, where plans for the redevelopment of council-owned land in south Tottenham – which have been reported to have sharply divided the Labour group – were discussed.
Cllr Bull had previously served as Labour chief whip for Haringey. Earlier this year, he sent an email to all 42 Labour councillors to express his “deep disappointment and concern about the level of both personal acrimony and discourtesy […] between colleagues”.
“Quite frankly, the level of unprofessionalism displayed by some, and it is very much only some, would leave residents – those people that we have been sent here to represent and are here to serve – speechless, and would reinforce the very justified, low opinion that they have of politicians,” the letter continued.
The Shylock character has been used as an antisemitic stereotype to portray Jews as avaricious and villainous.
Cllr Brabazon declined to comment. Cllr Bull could not be reached at this article went live.
A London Labour Party spokesperson said: “The Labour Party takes all complaints of antisemitism extremely seriously, which are fully investigated in line with our rules and procedures and any appropriate disciplinary action is taken.
"We cannot comment on individual cases."