A notorious jewel thief whose "prolific" campaign of raids was only stopped after he appeared on Crimewatch has been jailed after stealing rings worth £40,000.

Michael Walker is already serving a lengthy prison term for a string of thefts at jewellers in the north of England.

The serial robber has now been ordered to serve another 12 months behind bars after an audacious raid on Henderson Jewellers in Union Street, Dundee.

CCTV footage of the brazen crime on February 5, 2016 was played in Dundee Sheriff Court.

Father-of-one Walker, of Liverpool, was seen loitering in the shop's entrance alcove before opening a door and summoning a sales assistant.

She then followed him out of the store to look at rings in a window display before they both walked back in.

The sales assistant brought the items to Walker - who was standing directly below and facing a CCTV camera in the store.

Walker was invited to try on both rings and placed them on his pinky finger.

An accomplice - who has never been traced - then opened the store's door and Walker sprinted from the shop with the rings.

Fiscal depute Vicki Bell told the court: "The first ring is an emerald cut diamond in an 18 carat white gold band and is valued at £25,000.

"The second is a brilliant cut diamond set in a six core setting on an 18 carat white gold band and is valued at £14,500.

"The second man who came to the door was shouting 'come on, let's go' and in response the accused ran.

"He was never caught by the staff member who gave chase and was not traced by police.

"As a result the rings were never recovered.

"This offence was the first in a course of conduct that then followed at other jewellery shops."

Walker, 32, a prisoner at HMP Perth, pleaded guilty on indictment to a charge of theft.

Defence solicitor Susan Gibson said: "He is serving a two years and ten months sentence for thefts to a value of £150,000 imposed at Liverpool Crown Court in December 2016.

"He was in Aberdeen visiting a friend and had been to a casino and lost a lot of money.

"He is a gambling addict and was gambling on roulette machines.

"He was in a vicious circle and was in debt and these offences then occurred."

Sheriff Alastair Carmichael jailed Walker for a year.

Walker was featured on BBC's Crimewatch programme last summer as police investigated a series of thefts in St Helens, Warrington and York committed after the Dundee crime.

Walker - who previously served a four-and-a-half year jail term for a robbery in 2006 - was captured carrying out the "unsophisticated" crimes on CCTV and made full admissions after his mugshot was shown on the TV show.