Police investigating an assault in King Street, Twickenham, on Saturday morning launched a major manhunt.

The force helicopter as well as a marine unit on the Thames were called in to help following reports of a knifeman being on the loose in the town centre and riverside.

Met police helicopter circles above Eel Pie Island

The helicopter circled 300 feet in the sky above Eel Pie Island and along the riverside to Marble Hill park for several hours, much to the alarm of families, dog walkers, joggers and cyclists.

Police stopped worried residents and people from Twickenham Rowing Club leaving Eel Pie Island for a time while the search was carried out.

Force helicopter circled above the riverside for several hours (Credit @SkyCirclesLON)

Richmond Police said: "At around 8.40am police were called to an assault on King Street, close to Eel Pie Island in Twickenham.

"The believed suspect for an assault was located on a boat but refused to cooperate.

"Officers arrested the male after he was eventually persuaded to come off the boat.

"A Thames marine unit as well as the police helicopter were in attendance."