Graham Ennis thought he was just being a good citizen when he stepped in to help tackle a gang of teenage robbers.

Today he says he will think twice about taking such action again after police officers said the incident was not especially traumatic.

Mr Ennis, 59, suffered delayed shock and collapsed days after trying to make a citizen's arrest on two teenagers who raided the Brighton city-centre store where he was shopping.

When his health problems left him unable to attend a civil hearing at the county court, officials contacted the police to check his story.

In a memo to the court, later obtained by Mr Ennis, a PC confirmed that Mr Ennis had witnessed an incident between staff at the One Stop Shop in Queen's Road and other "members of the public" and had intervened, attempting to make a citizen's arrest.

Mr Ennis, of King's Road, Brighton, was horrified to read the officer's summing up of the incident, which stated: "I am not entirely sure what happened in this incident but can safely say that it was not so severe or dramatic it would traumatise a rational and normal person to any degree.

"At the time, Mr Ennis complained only to myself he felt shook up by the incident but, upon being offered medical assistance, he declined this. He did not say he had any physical injuries.

"Mr Ennis in my opinion appeared to be more excited than distressed about the whole incident, which left me feeling quite confused. Mr Ennis did not state at any time he had been mugged."

Furious Mr Ennis has now written to the Chief Constable of Sussex Police to complain.

He said: "The court wouldn't accept my medical certificate because of what the PC wrote and I had to turn up despite feeling rather unwell.

"I was mugged a year ago and I wasn't going to stand there this time and see this gang of little thugs terrorising the staff.

"I grabbed two of them and put my back against the shop door to stop about a dozen more outside coming in but, as soon as they saw their friends had been detained, they started trying to smash the door down.

"They repeatedly smashed it into my back and forced me to let go and they got away."

He did not realise until an hour later he was in a state of shock and his back was badly bruised.

Pat Sharman, the manageress of the One Stop Shop, said staff were taught not to intervene in potentially-violent situations and had been concerned Mr Ennis would inflame the situation by his intervention.

Sussex Police said they had responded quickly and fully to reports of an incident at the shop, sending about a dozen officers and driving Mr Ennis around to see if he could spot the teenagers.

A spokesman said: "He mentioned bruises when he called us but didn't want medical attention.

"Although I'm sure he was shaken up by what happened, the officer's honest opinion was the incident was not of the kind of level that would affect him a week later."