But even the imposing presence of an adult leopard at feeding time is not enough to get between plucky young Rattus Norvegicus (better known as the brown rat) and a free meal.

This extraordinary series of images were captured by photography student Casey Gutteridge, as he trained his camera on the leopard for a course project.

Excuse me? A perturbed Sheena the leopard lookson as a cheeky mouse nibbles her food at the Santago Rare Leopard Project in Hertfordshire...

The little rat - thought to be onlytwo to three months old - was spotted scampering into the leopard'senclosure shortly after feeding time at the Santago Rare Leopard Project, in Hertfordshire.

So intent was the plucky rodent on its mission to snatch a tasty snack, that it seemed not to notice that its path was taking it within a whisker's breadth of 12-year-old Sheena.

Clutching a corner of raw meat with its tiny paws, the rat busily tucked in, until it sensed one of those whiskers moving in.

Sheena, bemused by the interloper coming between her and the remains of dinner, padded over on paws big enough to wreak vengeance with a single swipe.

Rattus paused, lifted its dainty pink claws in submission, then - obviously deciding on a nothing-ventured-nothing-gained approach - continued to tuck in.

And after another tentative investigation, Sheena gave the leopard equivalent of a shrug and turned away.

...but even a gentle shove does not deter the little creature from getting his fill...

Mr Gutteridge, 19, from Potters Bar, Hertfordshire, thought the rodent was a mouse.

Mr Gutteridge said: 'I have no idea where it came from - he just appeared in the enclosure after the keeper had dropped in the meat for the leopard. 'He didn't take any notice of the leopard, just went straight over to the meat and started feeding himself.

'But the leopard was pretty surprised - she bent down and sniffed at it and flinched a bit like she was scared.

'It was amazing, even the keeper whohad thrown the meat into the enclosure was shocked - he said he'd neve rseen anything like it before.'

An expert at the Wildlife Trust said the creature was in fact a young and 'inexperienced rat', identifiable by its big paws and ears and more importantly its bald, scaly tail with a thick base.

Leopard project owner Jackie James added: 'My son threw meat in for the photographers and it just appeared. Sheena batted it away but it just came back. The determined little thing took no notice and just carried on.'

...so the mouse continued to eat the leopard's lunch and show the leopard who was boss