The sight of a police helicopter hovering overhead, not to mention a potential suspect fleeing in handcuffs, may well have given residents of a sleepy seaside town cause for concern.

But they would have been further surprised to discover that a major manhunt had been launched after four people were alleged to have been spotted engaging in sexual activity at a quiet beauty spot.

Devon and Cornwall police scrambled a chopper to scour Sidmouth after receiving a tip off that the quartet had been seen having group sex outdoors.

The onlooker claimed that one of the four was wearing handcuffs as they shed their inhibitions at the Byes, a picturesque local park more famed for its riverside walk and peaceful sanctuary.

Officers attended the scene but the alleged offenders managed to give them the slip, meaning that the force helicopter was dispatched from its Exeter base to track them down.

The aircraft hovered over the area for around half an hour on Monday evening as police searched for the two women and two men said to have been involved.

They later arrested a 20-year-old man from Sidmouth and a 28-year-old man from Plymouth, Devon, who were held on suspicion of escaping lawful custody and of committing an act outraging public decency.

A female from Exeter was also arrested but police said that no action would be taken against her. The second woman remains at large.

A police spokesman said: “They ran off when we arrived at the scene and so we had the helicopter assist us. It was suggested that one of them had been wearing handcuffs but none of the three had them on at the time of arrest

“Both men were bailed until next month. Investigations are ongoing with regard the fourth suspect, a female.”

Sidmouth is a quiet resort, popular with pensioners and known for its genteel charm and mild climate but it seems that such public frolics are not uncommon.

Stuart Hughes, chairman of Sidmouth Town Council, disclosed last month that a glass-fronted seaside tourist attraction, the Interpretation Centre, had become a magnet for those engaging in unsavoury behaviour.

“We’ve had reports of people getting completely naked and using the (open fronted) showers next door,” he said.

“Maybe someone has enjoyed it a little too much. Nothing surprises me. This sort of thing does happen.”

Mr Hughes added: “Perhaps Sidmouth isn’t as sleepy as people imagined. We are attracting all sorts of people at the moment.”