Kevin Heggarty, 19, targeted Michael McPhee as the 17-year-old walked home from a park in May this year.

Paisley Sheriff Court heard that McPhee, who suffers from cerebral palsy, had been playing football with friends at a park in the town.

As he walked home with his friends he stopped off to buy him and his pals some Irn-Bru.

Fiscal depute Kenneth Grieve told the court McPhee and his pal had been at Glencoats Park in Ferguslie and was left with £4 in change after buying the soft drinks.

He said they then went to a spot next to the railway line to drink their juice and that, whilst there, Heggary and another man appeared.

The prosecutor explained: “The complainer noticed the accused and another male “They became uneasy and began to walk in the opposite direction.

“The accused and the other male ran up towards them and stopped them.

“He moved close to the complainer and demanded his mobile phone from him.

“The complainer became very afraid and anxious due to the aggressive tone adopted by the accused and his very close proximity.

“The complainer advised the accused that he didn’t give his phone out to anyone.

“The accused made reference to being from East Kilbride and said he needed to phone his mum and dad.” McPhee believed that Heggarty was under the influence of drink of drugs because of how he was acting.

Grieve added: “The accused demanded the complainer’s phone and said, ‘I’m not f****** about, gees your phone’, placing the complainer in a greater state of concern.

“The accused thereafter said, ‘Gees your money’.

“The complainer became scared he was going to be hit and handed over £1.

“The accused said, ‘Do I look like I’m f****** about?’ “The complainer felt petrified and handed over all of his money - the full £4.

“The accused and his friend made good their escape.” McPhee went home and told his dad what had happened and they contacted the police.

They were able to help officers draw up an e-fit picture of Heggarty and, thanks to the image, he was identified, arrested and charged.

When he appeared in the dock last week he pleaded guilty to a single charge of assaulting and robbing McPhee near Paisley’s Blackstoun Road on May 8 this year, by pursuing him, repeatedly demanding his mobile phone, demanding money and robbing him of £4.

Sheriff Colin Pettigrew called for Heggarty, who is currently on remand at Low Moss prison, to be assessed by social workers ahead of sentencing and adjourned the case until next month.