Gerard Coyne lost to Len McCluskey by just 5,500 votes in the union leadership election

The man who fought Len McCluskey for the leadership of Unite will seek to overturn the election result this week by arguing that staff and resources at Britain’s biggest union were used improperly to help the left-wing firebrand win.

Gerard Coyne has filed a paper with the certification officer, the watchdog for trade unions, accusing McCluskey’s team of reactivating dormant Unite branches so they could endorse McCluskey.

The paper, seen by The Sunday Times, highlights how last year 59 branches got a new secretary “to facilitate [McCluskey’s] nomination”.

Coyne’s claim outlines what he says are 10 breaches of the rules. It also accuses McCluskey’s team of sending emails to union members containing “false information that certain union branches had nominated Mr McCluskey when in fact