A former city MP has had to shelve plans to enter the race to be Norfolk's first police and crime commissioner (PCC) – as he was once convicted of obstructing a police officer, he has revealed.

Ian Gibson, previously an MP for Norwich North, had wanted to stand as an independent candidate in the November elections for the county's first crime commissioner, who will replace police authorities and have the power to hire and fire the chief constable.

But Mr Gibson, 73, said he was unable to stand as a candidate because he has been convicted of an imprisonable offence which, according to guidance issued by The Electoral Commission, disqualifies him.

His conviction, for obstructing a police officer in the line of duty, which can carry a term of imprisonment of up to a month, saw him fined a total of �250 at Thetford Magistrates' Court in 1986.

Mr Gibson said he had been involved in a picket line at Thetford at the time of the Wapping dispute when the trade unions were fighting against Rupert Murdoch who was 'trying to kill off Fleet Street and take everything into Wapping'.

He said: 'The Sunday Times was being printed at Thetford.

'We tried to stop them distributing the papers on to the vans and I was picked up and two others for obstructing a policeman in the line of his duty.

'I got a �250 fine. I spent a couple of hours at Thetford Police Station and had my finger prints taken. I was teaching at the UEA then.' Mr Gibson, who was caught up in the expenses scandal in 2009 and resigned as an MP after being barred from standing as a Labour candidate at the next general election by the party's 'star chamber', said he was disappointed he could not enter the PCC race.

He said: 'I'm disappointed in a way, of course I am, but they make the rules.

'I think it could be a very positive thing to be working with the community and to take their views onto the police, not in a confrontational way, but in a way to sharpen it up. It seems to me the police service is one of the public areas that needs to be reformed.'

He added: 'A lot of people were keen on me having a go as an independent. I do believe it should be an independent who wins because party politics shouldn't win it.'