Lifeboat crew out on the River Thames were surprised after finding a pod of dolphins swimming next to their craft.

Members from RNLI Gravesend were returning to their station having arrived from Crossness, near Belvedere, at around midday yesterday.

However, the team were stopped in their tracks when they saw three dolphins swimming towards their boat in Northfleet.

It was originally believed the mammals were porpoises – a species resembling dolphins but with smaller mouths and spade-shaped teeth.

But the RNLI has since confirmed the species to be dolphins.

Crew member John Robinson was shocked to see them in the water.

He said: “It was an incredible sight. We spotted the dolphin-like fins at first [and] there were two adults and a calf.

“They were approximately two metres in length and incredible to witness right here on the River Thames, especially when they were jumping out of the water.”

Fellow crew member Ian Smith was equally delighted to see the marine mammals.

“We often see seals whilst out on the lifeboat, but dolphins are definitely on the rarer side of marine mammals we spot,” the Gravesend station manager said.

After watching the animals swim off, the team returned to Gravesend Reach shortly before 12.15pm.

It comes less than two months after a large whale was removed from the shore of the Thames.

The giant animal was found dead and had to be recovered three days later from Cliffe on the Hoo Peninsula.