This is the staggering moment a huge humpback whale surfaced - in the River Thames.

Shaun O'Riordan, 52, was at work when the massive mammal came to the surface for air this morning.

The animal appeared at around 7.30am and headed into the capital for around 40 minutes, before passing back through Dagenham, towards the sea.

Automotive worker Shaun said: "I've seen a few seals and even some dolphins but I've never seen a whale in the Thames."

It was spotted close to the Ford factory and experts said it has been in London since Sunday.

British Divers Marine Life Rescue said: "We observed the humpback whale in the Thames estuary for just just over three hours today (Sunday).

"The whale was diving and surfacing at approximately five to six minute intervals, slowly moving down river with the outgoing tide.

"We gave it lots of names today.

"The locals will have one, the press will have another. Will this one be male or female I wonder?

"Think Hessy has already been one of the chosen ones, like Nessy but less elusive."

An explainer

Humpback whales are one of the world's largest with adults range in length from 39 to 52 feet and weigh in at around 30 tons.

Known for their lilting song, humpbacks feed in polar waters, and migrate to tropical or subtropical waters to breed and give birth, fasting and living off their fat reserves.

The balleen whale's diet consists mostly of krill and small fish.