It was a case of being at the right place at the right time for off-duty police officer PC Mark Wallace, as a chance encounter led him to catch a whiff of cannabis and make an arrest.

PC Wallace was cycling on his way to work last Wednesday when he could smell something suspicious coming from a car at a lay-by near Melksham Oak Community School.

Little did the driver know that, underneath the cycling gear and hi-vis jacket, PC Mark Wallace, from the Roads Policing unit at Devizes Headquarters, was in his police uniform.

PC Wallace cycled around the corner before going back to the car where he saw a male light up an electronic device and called the police control room.

He said: “I went back down and described myself as an officer.

“I asked if he had any cannabis on him and he confirmed he did.”

The man was taken to Melksham Police Station where he received a street caution and was released without charge.

“Members of the public don’t realise that we are never off duty," said PC Wallace.

"When you join the police you sign up for 30 years you are working all the time.

“On or off duty you can’t ignore stuff and I couldn’t turn a blind eye.”