Former leadership candidate Michael Dooley launched the employment tribunal claim this week following the party snub.

Dooley claimed he has been victimised since unsuccessfully standing against general secretary Alan Ritchie in the 2009 leadership election.

He said: “In June 2009 I was a candidate in the election and after that I say I have been constantly victimised.

“The refusal to invite me to the office party was a petty, vindictive act and I feel embarrassed to bring the matter to court however there are several other matters which I am complaining about, such as the union withholding legal assistance from me and other matters.”

Ucatt denied victimisation and said that Dooley was not a member of head office staff although his office is in the same building.

The union decided not to invite Dooley or his colleagues to the party because they have not all taken up the invite in recent years. Dooley said he had consistently taken-up the invite over the last 11 years.

He is also claiming the leadership ballot was unfair and that only 56,000 union members received ballot papers out of a potential electorate of 130,000.

The tribunal at Croydon South heard how Dooley has been the subject of several union enquiries and has now been suspended.

The Tribunal will now make their decision if the claim will go to a full hearing listed for 5-6 days next year.

A UCATT spokesperson, said: “At the hearing the Employment Tribunal judge reserved his decision. This will be sent to all parties. Until then it would be inappropriate for anyone to comment.”