Judge Bill Dunlop sentenced Sean Henry, who is has a high risk of re-offending, to four years and four months.

Henry will also be monitored after his release for three years in order to protect the public.

Judge Dunlop told Henry: “Your appearance on CCTV seems to confirm this was a stupid, almost inept performance. However, it must have been a frightening experience for the shop workers.” The High Court in Glasgow heard today that Henry's bid to raid Ritchie's Newsagents in High Street Johnstone, on May 2 was foiled by a shop assistant who picked up a large pole to ward him off.

Henry, 26, armed himself with a large sheath knife and walked from his home to the shop.

But, the 200-yard walk attracted attention because, despite it being a warm day, Henry was wearing a green Celtic Legends scarf wrapped round his face so that only his eyes were visible.

One woman was so concerned she kept watch on him. Shop owner Neil Murray, 45, was also alarmed by the way window cleaner Henry, of Ellerslie Street, Johnstone, was hiding his face.

Mr Murray told his assistant Sharon McGhee about his concerns just seconds before Henry walked into the shop brandishing a knife.

In court, Henry admitted assaulting Ms McGhee and Mr Murray at the newsagents by brandishing a knife at them and repeatedly demanding money with intent to rob them.

Advocate depute Alison di Rollo, prosecuting said: “The accused was repeatedly shouting: 'Give me the money.' “He was holding the knife in one hand and a blue bag in the other. He brandished the knife at Ms McGhee and Mr Murray and she picked up a large pole to ward off Henry.” The court heard that Henry then ran off.

Police who later viewed CCTV footage of the incident recognised Henry and he was detained the next day in the street.

Henry was wearing odd shoes and he asked if he could be taken by police to his flat to change.

He changed into a pair of Adidas LA trainers that the detectives noted were the same ones worn during the attempted robbery.

A warrant to search Henry's home was obtained and the Celtic Legends scarf was found under a floorboard in the living room.

Initially, Henry denied the offence, but then admitted his guilt telling police that he owed a drugs debt of £1,000 and committed the offence in a bid to obtain money to pay this off.

The court was told that Henry has numerous previous convictions including one from 2009 for robbery with a sword for which he received four years in jail.

Defence counsel John McElroy said: “This was a stupid thing to do. Totally stupid. The only planning involved was covering his face with a scarf. He pled guilty at the earliest opportunity.” The court heard that but for his early plea Henry would have been jailed for six years.