A naked duo were spotted taking a dangerous dip in the River Thames at Deptford in the early hours of the morning following the hottest July day in history.

The RNLI Tower lifeboat crew were called after a nude man and women were seen cooling off in the river near Borthwick Wharf at 3.39am on Thursday (July 2).

Officers onboard a Met Police boat patrolling the River Thames helped track down the skinny dippers after seeing them fleeing the water into some bushes.

Shortly after, one swimmer emerged from the shrubbery with some clothes on to explain their actions.

The bare-all bathers, who were unhurt, were warned of the danger they had put themselves in and were urged not to make a repeat performance.

One officer posted on Twitter from the Met Police boat account (@MPSonthewater): "Two naked persons located after a search with @TowerRNLI.

"Hot weather, alcohol and river swimming.

"Overheard saying they were mermaids #badidea."   

On Wednesday, the mercury hit 36.7C at Heathrow making it the hottest July day on record, according to the Met Office.

The RNLI charity has urged people not to swim in the river following the incident.

Kevin Maynard, Tower RNLI lifeboat station manager said: “London may be gripped by a heatwave but swimming in the River Thames is incredibly dangerous and we would strongly advise people not to do so.

“These two skinny dippers were lucky to escape unhurt as they had put themselves in a potentially life or death situation.

“The River Thames in London has very strong currents that can easily sweep you away.

“Combine this with the high number of obstacles in the river and swimmers can all too easily find themselves dragged under the water.”

Mr Maynard also warned of the dangers of cold water shock, which can cause uncontrollable gasping for air, leading to gulping down water and causing a risk of drowning.

He added: “If you’re suffering from the heat there are better and much safer ways to cool down than putting your life at risk by swimming in the River Thames.”