The ‘big cat’ sighted around Crystal Palace twice in recent weeks and dubbed the Palace Puma - is definitely not a puma and may well be a big black labrador.

Neil Arnold, of Kent Big Cat Research, who has been looking into big cat sightings for over a decade, explained that it cannot be a puma as they are not black, but might be a black leopard or jaguar, the slang term for which is panther.

But Eduardo de Brito, who lives in Thicket Road very close to the second sighting, told a reporter for the Streatham Guardian on Friday that he is convinced the ‘big cat’ is actually a huge black dog.

He said: “It's like a labrador. He scares everyone! When I stop my car I am afraid to get out if he is about, he's massive. My friend has seen it too, and he is scared. It's really scary, especially late at night or early in the morning.”

The theory is backed up by the fact that both sightings were during the day when big cats usually lie up, often in trees. Mr Arnold said: "They are very elusive animals also, mainly hunting at dusk and throughout the night."

Residents have been intrigued by two recent sitings of what has been dubbed the "Palace Puma". On Saturday, August 8, journalist Helen Barrett says she saw a big black cat in woods while she walked with her family in Church Road woods. Then two teenagers said they saw a cat "the size of a great dane" walking near Crystal Palace Park.

Mr Arnold, whose investigations cover much of south-east London and Kent, estimated there could be as many as 15-20 panthers, pumas, lynxes or jaguars on his entire patch. He has received an average of 200 reported sightings of massive moggies every year for the past 10 years and reckons "well over 100 of those are credible".

Natural England, the government agency keeps a register of big cat sightings and encoruages members of the public to report any sightings of unusual animals.

Strangely, however, when this newspaper checked whether the register included the recent sightings at Crystal Palace, and the ‘Beast of Sydenham Hill’ in 2005 - both investigated by the police - neither was included in the register.

If there is a Palace Panther, is it dangerous?

According to Mr Arnold, big cats on the loose in Britain survive on a diet that includes rabbits, foxes, deer, mice, rats, pheasants, pigeons, livestock, domestic cats, sheep and squirrels.

He said they are very secretive, sleeping in trees during the day and only emerging to hunt at dusk. They rarely leave remains of their kill and their footprints are often mistaken for dogs - the key difference is that claws will be visible in dog prints.

According to Mr Arnold, British big cats are mostly nocurnal and solitary, but day-time sightings do occur, as with the palace puma.

He insists that big cats pose little danger to the public. He said: "The advice I give to people is to maintain eye contact and back away slowly. Will only ever attack someone if backed into a corner."

The two government departments with responsibility for big cats, the Home Office and the agriculture department DEFRA both refused to provide any guidance to the public on what they should do if they see a big cat.

In 1995, then agriculture minister Angela Browning commissioned a high-profile report into reported sightings in Cornwall of a big cat dubbed the 'Beats of Bodmin Moor'.

The report concluded that the existence of wild big cats in Britain could not be disproved, though most sightings and footprints were likely to be from domestic cats and dogs.