Nathan Welch worked for Dacorum Borough Council, which has refused to say whether this is still the case.

The 35 year old answered bail at Hemel Hempstead Police Station on Monday (June 30) following his arrest in January this year.

It is understood the former Royal Marine, of Penrose Court in Grovehill, Hemel Hempstead, bought the weapon from an internet auction site.

Stun guns, illegal in this country, are used to temporarily disable victims by delivering an electric shock.

In his position as a council officer Mr Welch worked with young people on special projects to help steer them away from antisocial behaviour.

He has been involved in a number of activities including helping youngsters to build an animal farm in Bourne End and teaching boxing in Bennetts End, Hemel Hempstead.

A Herts Police spokesman said: "He was arrested on January 9, 2008, after having committed the offence in June 2006."

Although a caution is not a criminal conviction it is recorded on a police database and can be flagged up in a Criminal Record Bureau (CRB) check - something that people who work with children are often subject to.

A council spokesman refused to comment on the matter.

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