What would you say is the UK’s least known mammal? The wild cat? The pine marten?

No, it’s a creature so obscure that a large proportion of the population don’t even realise they are sharing these isles with this stinky and secretive beast.

The mystery animal is, of course, the peerless and pongy polecat.

Yes, old stinker is back from the brink. An animal so rare that it was once reduced to a tiny population clinging on in West Wales has fought back and swelled its ranks to numbers approaching 50,000 while expanding its range both south and eastwards.

And, yes, it’s here in Dorset. Indeed, members of the Bournemouth Natural Science Society have gone so far as to say it is “now common in most of Dorset and Hampshire, especially in the river valleys.”

And according to Dorset Wildlife Trust, there have been an increased number of sightings in the last decade, with activity along the river Frome, the river Piddle and the river Winterborne south of Blandford.

“We have noticed a steady increase in sightings in recent years,” said Steve Davis, volunteer programme manager at Dorset Wildlife Trust.

“These have been centred around the Poole, Wareham and Bere Regis areas although this year has also attracted several records from North Dorset and the Dorchester area.”

He added they are a challenge to see as they are very strictly nocturnal, are very secretive and ‘move like greased lightning’.

“As such, any survey for this mammal usually entails recording of roadside carcasses,” he said. “This is useful as an indicator of the population status in a particular area. This time of the year heralds an increase in sightings of polecat carcasses, as the youngsters start to venture off in search of new territories.”

But why is the polecat so little known in the first place? Why has it struggled so much and how has it fought its way back?

First things first, when considering the polecat, it is impossible to discount the pong.

The clue is in its scientific name - Mustela putorius. Putor in Latin means foul smell.

Polecats have scent glands either side of their nether regions which they use to make a pungent and impressively repellent scent.

The animal, a large relation of the weasel, was, until the 19th century, found throughout mainland Britain.

Like other members of the mustelid family, its fate was nearly sealed through its very thick, very warm and therefore very desirable coat.

Polecats were killed in their thousands for their pelts - this, coupled with persecution from gamekeepers and ongoing habitat destruction, led to the population falling to catastrophic levels of around 5,000.

But a few decades ago the polecat’s fortunes began to change.

In the early 1980s the species was afforded protection under the Wildlife and Countryside Act and four years ago was added to the list of Biodiversity Action Plan species.

The polecat has slowly but surely recovered its numbers with an estimated 48,000 now at large in the British countryside, including here on the south coast.

Laura Drake, surveys officer at the Mammal Society, says: “The return of the polecat is a real good news story.”

Details on how to record sightings at dorsetwildlifetrust.org.uk/dorset_mammals_project.html or send them to Twitter @Dorsetwildlife