Ryan McCoshan left Peter Brown permanently disfigured after striking him with the deadly weapon outside his gran’s house in Ashton View last September.

Prosecuting, Martin Macari told the High Court last week how McCoshan lost the plot, leaving his victim with ‘horrific injuries’ after the sword sliced into a bone in his arm.

The 26 year-old father-of-one was left raging after his delivery driver questioned how long it had taken him to answer the door.

Mr Macari told the court Mr Brown, 63, was working for a Chinese takeaway in Dumbarton and was called to deliver a meal to McCoshan’s house. When the driver turned up with the food a ‘heated argument’ soon broke out between them.

Mr Macari added: “Mr Brown knocked the door, but received no answer. After a few minutes, the door was answered by McCoshan. An argument then took place over the length of time it had taken for the door to be opened.” After paying the delivery driver, McCoshan swore at him and Mr Brown took exception to this – McCoshan then ran upstairs, only to return wielding a samurai sword.

He lashed out at his stunned victim, striking him on the arm as he tried to defend himself. As the assault continued, Mr Brown’s friend, William Towie - who had been sitting waiting for him - grabbed a nearby For Sale sign and charged at McCoshan to help the victim.

McCoshan’s gran also came to Mr Brown’s aid striking her grandson in a bid to end the attack.

The thug eventually stormed back inside the house leaving his bleeding victim for dead.

Police and ambulance staff soon arrived and Mr Brown was rushed to hospital where he needed a blood transfusion and vital surgery following the brutal attack.

It emerged a bone in his arm had been sliced into as a result of being struck. A total of 37 staples were needed following an operation. He has been left badly scarred and has nerve damage which could prove to be permanent.

The court heard he can no longer work and has difficulty carrying out simple tasks such as dressing himself, due to the loss of strength in his arm.

McCoshan was eventually arrested after police found him hiding in the loft of his house.

Judge Lady Rae told McCoshan: “This was a vicious attack on an elderly man going about his business.” McCoshan admitted assaulting Mr Brown to his permanent disfigurement and impairment. He was remanded in custody and will learn his fate at Edinburgh High Court on May 13.

READ PETER BROWN'S OWN ACCOUNT OF HIS HORRIFIC ORDEAL IN TUESDAY'S REPORTER....