Matthew Gates told the Cardiff hearing that his supervisor, Ron Bradbury, had subjected him to a series of sexual remarks and acts, including grabbing him from behind and simulating intercourse. He said: 'I was appalled. I ran to my motorbike and he said: 'I nearly had you that time, didn't I?'.'
The tribunal ruled that Mr Gates, 21, was a victim of sexual discrimination. He was awarded pounds 3,000 for the loss of his job and a further pounds 1,500 for 'injury to his feelings'. The maximum possible award is pounds 11,000.
The tribunal chairman, Allen Rees, described 50-year-old Mr Bradbury's actions as 'unwarranted, unreasonable and offensive'. He said: 'It went well beyond what would be accepted as horseplay - especially when it was going on most days of the week.'
The tribunal heard that the incidents occurred while Mr Gates, of Cormorant Way, Duffryn, Newport, was working with Mr Bradbury for Security Express Guards at the Alpha Steel plant in Newport, Gwent.
Mr Gates complained about Mr Bradbury's behaviour to superiors and was told that he could go to another location or lose his job. He agreed to move to a nearby building site where he worked longer hours for less money, knee-deep in mud. Soon afterwards he left the firm and is now unemployed.
Another security guard said he had seen Mr Gates being grabbed by Mr Bradbury, who had seemed to derive sexual pleasure from bouncing another male colleague on his knee.
Paul Jacomb, branch manager, said that he had cautioned Mr Bradbury about his behaviour but had felt it was 'barrack-room humour'.
After the hearing, Mr Gates said: 'It was never just horseplay. I tried not to take any notice at first but then I was offended.' He added: 'There was a similar case in Southampton three years ago when a woman supermarket worker suffered in the same way - she got pounds 7,000. I was sexually harassed equally, but because I'm a man the court hasn't compensated equally.'
A spokeswoman for the Equal Opportunities Commission said yesterday that she believed it was the first successful sexual harassment claim brought by a man against another man. 'We are delighted he has won. This was unacceptable behaviour.'
Mr Bradbury still works as a security officer at the steel plant with another company that now has the contract. He said: 'I've no comment to make apart from that I'm taking legal advice.'