A gang of armed robbers, one of whom wore a clown mask, attacked at 22-year-old man at a house in Colney Heath and held his mother captive.

One of the robbers, 30-year-old Joshua Munnings of Waldegrave Road, Crouch End, London was sentenced to 12 years and nine months in prison today at St Albans Crown Court, after pleading guilty to aggravated burglary.

The robbery took place at 9.15pm on Monday, December 18, last year, when five men forced their way into a house in High Street.

Prosecutor Peter Shaw told the court that the son answered a knock on the door and was confronted by a man in a clown mask brandishing a knife.

He said: “Four others came into sight and forced their way in. Three had large knives and the fourth what appeared to be a firearm in a white sock.

“Three took the son upstairs saying they had come to seize money, which was a mystery to him. The man with a gun and one with a knife stayed in the conservatory with the mother.

“They found a safe upstairs and threatened him [the son] to open the safe. He couldn’t think straight and couldn’t think where the keys were.

“He did find the key and was told to open the safe. He did and thought he was going to get murdered because there was nothing in it.”

The son had his iPhone 6S, Playstation, Citizen watch, bank card and passport taken by the gang. His friend who had been playing computer games with him hid in the shower throughout the robbery.

The son was also stabbed in the lower chest, requiring five stitches, and suffered a cut to his little finger and a black eye.

His mother, whose jewellery had been stolen in a previous burglary, was pushed into the conservatory and watched as her home was ransacked. Mr Shaw said that a wig which had belonged to her late mother who underwent cancer treatment was handled in a “disrespectful way”.

She made as much noise as possible to alert her neighbours, and the man with the gun said he would “burst her” if she did not stop talking, and claimed to have two bullets in the gun.

In a victim impact statement the mother said: “I cannot describe the fear I felt inside. It was as if I was witnessing something that came out of movie. The gun was constantly moving and was pointed in my face.”

She said that she lost her job and had to move out of her home, as did her son. She also said that the raid contributed to her father’s suicide this year.

Police have not found the other four men, and caught Munnings because of a fingerprint he left on a money box in the house.

He was arrested on Sunday, June 10 as he was boarding a Eurostar train at St Pancras, and was found to be carrying more than £2,000 in cash. He had seven convictions for 12 previous offences.

Defending Munnings, David Martin-Sperry said he did not know what was going to happen when he went to the house.

He said: “He did not know the background. He said he was misled. He thought they were going to see one of their own number who owed some money. It was a piece of debt collecting of other people and he was simply invited along.”

Munnings had slept on the street for two years prior to the offence and was the one robber who was not armed.

Judge Philip Grey said: “This was the worst nightmare of every law-abiding householder”, and said the victims had been subject to a terrifying ordeal which was a “gross violation of the family home”.

Munnings was given a sentence for nine years and nine months with an extension of three years, meaning he could be recalled to prison on his release at any time up to 2031.

The money seized from Munnings will go to the mother and son as compensation.