“Absolute madness” took hold on the Heath last Thursday as, with the Parliament Hill Lido unexpectedly closed, swimmers keen to escape the sweltering temperatures headed for the model boating lake instead.

Ham & High: Swimmers invade the model boating pond on Hampstead Heath.Swimmers invade the model boating pond on Hampstead Heath. (Image: Archant)

Over-eager Heath denizens braved the murky waters of the boating pond, even though Heath by-laws prohibit swimming except for in the three bathing ponds during opening hours.

One disgruntled passer-by said: “The lido was shut early and people were unable to get into the ladies’ pond as it was too busy.

“Some people were doing it and others just kept getting in. Absolute madness.”

A spokesperson for the City of London Corporation said: “Entering the non-swimming ponds on Hampstead Heath is extremely dangerous and these ponds do not have lifeguards present.

Ham & High: Swimmers invade the model boating pond on Hampstead Heath.Swimmers invade the model boating pond on Hampstead Heath. (Image: Archant)

“The unsupervised ponds have uneven banks, varying depths and hazards such as reeds, weeds and objects on the bottom.”