UNITE has urged a top charity boss to resign after a “shameful” misdirected email showed that he is trying to “erode” union support in the workplace.

Howard Sinclair, CEO of homelessness charity St Mungo’s, sent an email which suggests he was working with BLJ London, a prominent PR consultancy firm, to stop people at the charity joining Unite.

The message, which was accidentally sent to the inbox of a Unite official, said that there was “no need” for the company to “change tac [sic]” after an industrial dispute this summer regarding proposed change that could lead to pay cuts and job losses.

He said that “our strategy” must be to “stop more people joining” Unite and “erode” its support among the workforce.

Mr Sinclair is due to stand down in autumn 2020 after six years at the helm, but Unite is urging him to resign immediately.

The call comes as the union begins re-balloting for strike action after failing to reach the legally required 50 per cent threshold by a single vote — despite 78 per cent of members voting for strike action.

Unite regional officer Tabusam Ahmed said: “Christmas is a time for giving, but donors and funders of St Mungo’s are unlikely to be thrilled that the charity has paid for the services of a top London PR agency ‘to break’ the union during this summer’s dispute.

“This email blunder has exposed Sinclair’s true colours. He must now do the decent thing and step down immediately to clear the way for negotiations to re-start with a clean slate.”

A St Mungo’s spokesperson acknowledged that Mr Sinclair is stepping down in 2020 and said: ”St Mungo’s is not reducing pay, nor making any changes to staff terms and conditions and we have made it clear to Unite officials that we are waiting to talk about the proposals we made in the summer and there is absolutely no need for them to push their members to strike.

“St Mungo’s formally recognises both Unison and Unite and we actively encourage our staff to join the union of their choice and participate as they choose.”

They said: “As is normal for a charity our size, we work with a variety of external partners including on legal and media issues.”

“[The charity’s] first priority is to protect our vulnerable clients, especially through the winter months. Unite officials’ threat to strike has a direct impact on our organisation and our clients.”