Former Wisbech mayor Jonathan Farmer has been found guilty of the illegal possession of a firearm.
A jury at Cambridge Crown Court took less than 30 minutes to deliver their verdict after a two day trial.
Farmer, 56, a Wisbech town and district councillor, of South Brink, Wisbech, was bailed pending sentence but warned he could expect to go to prison.
Judge Gareth Hawkesworth ordered Farmer to stay at his home address and cautioned him 'to co-operate with pre-sentence reports'.
The judge told him: 'Your sentence carries a minimum term of imprisonment unless exceptional circumstances apply. You must expect a custodial sentence.'
Farmer appeared stunned after the jury delivered their verdict at 4.30pm.
Within the last few minutes Farmer, accompanied by his wife Susanah and fellow town councillor Steve Tierney, left the court building without comment.
He will be sentenced on August 29
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here