Alan Sargeant is trying to find out more about the killer’s time in the Highlands, suggesting he might have been secretly working for the British authorities.

The 49-year-old has pored over old newspaper clippings and books in a bid to build a picture of the criminal’s movements north of the Border.

Toplis was the most wanted man in Britain in 1920 after he went on the run following the murder of a taxi driver in Hampshire.

He ended up entertaining guests at an Inverness hotel as a piano player and later worked as a labourer at a Dunmaglass farm, some 15 miles south of the city.

After about a month in Scotland he made his escape by train to Cumberland, where he was shot dead in a gunfight involving three police officers and the chief constable’s civilian son.

His story was dramatised by the BBC in 1986 starring Paul McGann.

Last night Mr Sargeant, who was born in the same Derbyshire town as Toplis, said he believed the one-time soldier might have been a government informant.

He explained: “Who better to infiltrate militant and nationalistic movements raising their heads than somebody who was a cult figure from the war, a ringleader of a famous mutiny - or at least had been painted to be?”

Toplis was a serial deserter and should have been executed by the firing squad but kept returning to the Army ranks often under his real name posing as captain wearing a monocle.

In 1917 he was posted to a base in Etaples, northern France, and allegedly led a six-day mutiny although some accounts suggest he was nowhere near when trouble broke out.

However, he became a figurehead with an air of mystery known for a number of disguises, and after he went on the run for the fatal shooting of a cabbie in Andover, made his way to Monmouth in Wales via London before cropping up in Scotland.

Mr Sargeant said: “It is likely he would have been sheltered by other deserters and militants.

“If he was so desperate to remain undetected why did he choose to spent time in cities where newspapers were readily available for people to read about the manhunt?

“Another curious aspect is that for a man who had seemingly never been to Scotland before he knew his way around at a reasonable ease and was almost certainly getting lifts from people.”

Toplis arrived in Scotland in May 1920 and spent time in the Grampians and Highlands picking up jobs here and there.

He is known to have spent time in a remote bothy in Tomintoul, Moray, before a stay at the Temperance Hotel in Inverness entertaining guests under a false identity as a pianist.

After he fled the hotel without settling his account he eventually made his way back to the bothy where he was involved in a gunfight before fleeing towards Aberdeen.

Mr Sargeant, who runs a web business in Craigellachie, Moray, said everything about his escape pointed towards him being a trained operative who knew counter surveillance measures.

He said another Etaples mutineer, a Scotsman by the name of James Cullen, also escaped punishment and became an informant adding it was possible Toplis had followed suit.

“The special branch of the day would have been interested in various organised movements in Scotland and around Britain from the Suffragettes to the Communist Party, various militant movements which were linked to unions and the raising nationalism north of the Border - anything that could have been seen as a threat,” he concluded.

“I think Toplis may have been an informant and had a network of people around him, whether they were criminal or not I can’t say, who harboured him yet it appears somebody tipped the authorities off about his whereabouts when he was in the bothy.

“It is my speculation only but I think he could have been an informant which would explain his actions during his ‘cleaning run’ to Aberdeen with abrupt changes to his journey, changes to his means of transport and even accounts of him telling a lorry driver he knew his way around the well-to-do area of Bieldside in the city.

“I’m still interested to find out more about his movements especially in Scotland and I’m particularly interested in learning where exactly the Temperance Hotel was.

“Toplis certainly was no hero. If anything he was a loose cannon and a dangerous man but I think there is more to this story than meets the eye.”