The witching hour was upon Hampstead Heath at first light this Hallowe’en when a gathering of sorceresses descended upon the Ladies’ Pond for a chilling morning swim.

A spooky spectacle of 35 women in pointy hats, apparently seen hovering over the water, greeted early-morning swimmers yesterday.

One onlooker speculated that since the ladies looked like they were floating they must be supernatural beings. The ability to stay above water was considered proof of paranormal powers during the Salem Witch Trials in the 17th century.

However, those who brought their brooms along did not quite manage to fly, plunging into the water rather than taking off.

Out of the waters, the so-called Kenwood Coven plotted over goblets of a hot potion brewed up on the wooded banks of the pond.

But unless a spell was cast over the water to warm it up, perhaps the only weird characteristic of this sisterhood is their resilience against the icy cold water of the Ladies’ Pond early on a chill autumn morning.

“The swim brought out some magic in what can be a bleak winter world,” said convener Sophia Luminati.

“The pond, surrounded by the thick woodland, was seriously enchanting, and the ladies were ecstatic and delighted after the event.”

Ms Luminati, a regular winter swimmer, said an icy cold dip does have a certain “supernatural” effect. “Witchcraft is all about the power of transformation and being immersed in the cold waters of the pond awakens something in our bodies.

“Shamans used immersion in cold water as a way of healing people and you do feel transformed, physically and mentally, after a cold swim.”

She added that it felt like a celebration of life – quite the opposite to All Hallows’ Eve’s traditional associations with ghosts and ghouls.

The seasoned pond swimmer and her friend have been donning their pointy hats all month, giving a fright to local photographer Ruth Corney who spotted a pair of witches during her regular morning swim last week.

Ms Corney, whose photos appear in Taking the Waters: A Swim Around Hampstead Heath, has been snapping the park for 15 years – with the Ladies’ Pond a favourite subject – but admitted this was her strangest sighting yet.