Sherlock Holmes made Dartmoor infamous

Perched 1,500ft up on wild moor land, the jail's grey granite walls even prompted a shudder in the current governor when he first approached them.

These bleak walls are in fact the only part of the prison which actually date back to the original Napoleonic-era prisoner of war camp. Most of the listed structures inside this high stone ring were actually built between 1871 and 1912.

The austerity of the architecture was never consciously intended to oppress inmates, says Allan Brodie, co-author of a new English Heritage book on the country's prisons.

Imposing

"The grey granite was used because it was the locally available building material. Dartmoor was intended to be a large and secure prison, so the buildings are big. That scale makes them imposing."

Mr Brodie says it is largely the prison's setting that lends Dartmoor its dismal air. Some 16 miles from the nearest railway station, even HM Prison Service admits the institution is "somewhat remote".

One of the most dreary wastes ... as far as the eye could reach

Dartmoor inmate Joseph Bates

The prison was first established to house French combatants captured during Britain's campaigns against Napoleon.

Prisoners of war had been held on ships in Plymouth harbour, thought dangerously close to arms warehouse should they stage an escape en-masse.

In 1806, Dartmoor was selected as possibly the most remote and harsh location in southern England.

'Dreary'

"On these three sides, one of the most dreary wastes, studded with ledges of rocks and low shrubs, met our view, as far as the eye could reach," wrote Joseph Bates, one of the American PoWs sent to Dartmoor when Britain went to war with its former colony on 1812.

Following the end of hostilities, Dartmoor was closed for 25 years. It was only pressed back into service as a criminal prison when the ending of convict transportations to Australia put the whole penal system under strain.

The remoteness which made Dartmoor ideal as a PoW camp, did not lend itself well to this new role and set it apart from the Victorian's city jails.

Dartmoor has been the scene of unrest

Thanks to the lack of public transport on the moor, a term in Dartmoor often means that inmates may not receive regular visits from loved ones.

Having taken a taxi for the final leg of her 6-hour journey to see her fianc�, one visitor said: "[The driver] told me he usually only sees fares to Dartmoor once. They never come back again."

The moor's unusual "micro-climate" also makes Dartmoor a trying place to live. When the sun came out for Mr Brodie's photographer, the governor described it as an event "bordering on the miraculous".

Ray of light

"They told me I could go to a nice warm prison if only I would admit to murder," said one-time inmate Stephen Downing - whose conviction was quashed after 27 years spent behind bars maintaining his innocence.

Mr Brodie says that just because Dartmoor is of Victorian vintage, the building itself isn't necessarily unfit for habitation in the 21st Century.

While one cell block lacks "integral sanitation" - the prison service jargon for flushing toilets - recent months have seen money allocated for a new library and gymnasium.

Newer prisons lack Dartmoor's light and space

"In terms of living, staff and inmates often prefer Victorian prisons such as Dartmoor to those built in the 1960s and 70s."

Newer "hotel" prisons are often split up into floors, rather than having the open galleries and landings seen at Dartmoor.

"The 70s prisons have lots of dark areas and lack natural light. This tends to make everyone feel less safe and secure. In comparison Dartmoor was very busy, like going up Oxford Street," says Mr Brodie.

"Having a good building is not enough to make a good prison. Dartmoor is not a bad building - it's just in a bad place."