The Enquirer has seen the complaint letter sent to Ucatt’s HQ by the pensioner who is also a member of rival union Unite.
The letter recounts alleged events at a meeting to discuss the industry’s blacklisting scandal.
The letter states: “He headbutted me just outside the door and I fell on the floor.
“Whilst I was on the floor he repeatedly kicked me in the ribs. Fortunately onlookers, intervened and separated us.”
Ucatt has yet to comment on the matter.
Former Ucatt leadership candidate Mick Dooley, who was speaking at the meeting, said: “If the allegations are true it will only be one more episode in the recent sorry saga of the builders union Ucatt which appears to lurch from one embarrassment to the other without any shame”