A post-mortem has shone light on the death of a sperm whale that became stranded in The Swale.

The huge creature sadly died on Saturday, two days after it was first spotted off the Whitstable coast.

Experts investigate the stranded sperm whale (Video: CSIP/ZSL)

Experts from the Cetacean Strandings Investigation Programme (CSIP) carried out a post-mortem at the Peel Ports in Sheerness on Wednesday.

Their examination revealed the whale was a "sub-adult" - which had passed through the juvenile period but had not yet attained typical adult characteristics - measuring more than 40ft in length.

They found there was no evidence it had recently fed, after examining two of its four stomachs and finding them to be empty.

CSIP experts said: "The lack of any squid beaks in the stomachs potentially indicates that the whale may have been in the southern North Sea for some time."

Although there was initially speculation the creature may have died after swallowing plastic, experts confirmed no marine debris or plastics were found in its gastrointestinal tract.

Zoological Society of London's Rob Deaville, CSIP project manager, said: "The findings are consistent with live stranding of an out of habitat individual.

"Sperm whales are normally found resident in much deeper waters and the southern North Sea can be considered an abnormal habitat for the species as they are unable to feed there.

"Sperm whales have previously been recorded stranded in south-east England, including a very similar case in Kent in February 2014.

"That’s the value of monitoring programmes like the CSIP. Now with 30 years of data, we can gain real insight into the wider health of the marine environment and the frankly extraordinary wildlife that can be found around UK shores."

The sperm whale first hit headlines last Thursday when it was spotted off the coast near Whitstable, before finding its way towards Harty Ferry, Faversham and the Isle of Sheppey.

That afternoon, the whale began swimming with the rising tide into The Swale - a tidal channel of the Thames estuary.

It had found itself trapped in shallow waters and become "distressed and confused".

Sperm whales are a deep water species not usually found around the UK, and experts said its chance of survival was just 1%.

Medics from marine animal charity the British Divers' Marine Life Rescue monitored the whale's movements and behaviour, but on Saturday sadly confirmed it had died.

It was originally thought that the creature was a minke whale or possibly a humpback, but inspection of photos taken by eyewitnesses concluded that it was a sperm whale.

They have distinctive features including massive heads and prominent rounded foreheads, according to National Geographic.

The whales have the largest brain of any creature known to have lived on Earth.

Escaped animals, unusual finds and news from the RSPCA can all be found here

Read more: All the latest news from the Isle of Sheppey

Read more: All the latest news from Whitstable

Read more: All the latest news from Faversham