A bank robber was caught red-handed thanks to a quickthinking cashier and an off-duty policewoman.

James Reilly bluffed his way through a string of raids unarmed in London and along the South Coast by passing notes to bank and building society staff claiming he had a gun.

He faces years behind bars after he was captured in central Brighton earlier this year.

Reilly, 45, from Wandsworth, walked into Royal Bank of Scotland in Castle Square, Brighton, on March 4 and handed a business card over the counter. The message read: "I'm armed, 3k now".

The bank clerk handed over the cash but slipped a packet of security dye among the notes.

Reilly left hoping to make his getaway by bus but the packet exploded and he was left covered with red dye.

PC Andrea Leahy, who was off-duty and shopping with her partner at the time, recognised the ink as the tell-tale sign of a robbery.

They each grabbed an arm and kept him in nearby Palace Place until back-up could arrive.

Within minutes he was surrounded by armed police.

Reilly admitted carrying out the robbery on March 4 this year, at Hove Crown Court yesterday.

He also pleaded guilty to two more robberies in London which took place in the fortnight before he was caught.

At Lloyds TSB in Tooting on February 22, he stole £2,110 after handing a note over the counter which read: "I am armed and I will shoot."

At a Nationwide branch in Streatham on February 27, he took £1,450 after passing a note to staff saying: "I will shoot the next customer".

Judge Anthony Niblett told Reilly: "A lengthy custodial sentence is inevitable."

Reilly had 29 previous convictions for crimes including robbery when he was captured. He was out of prison on licence from a six-year sentence handed down in 2003 when he committed his latest crimes.

Tony Loader, defending, said he should get a shorter term because he did not really have a gun.

He said: "He was not armed. He did not have anything in his possession which could even remotely be considered a weapon.

"That does not remove the fear from the cashiers, but it is a factor."

Judge Niblett adjourned the case until July 1 while probation officers prepare a report on the danger Reilly poses to the public.

An Argus reader captured the arrest on camera.

One onlooker said: "I came around the corner and there were armed police and a man was clutching what looked like a load of £50 notes covered in red dye."

After the raid, Chief Inspector Laurence Taylor praised PC Leahy's actions.

He said: "She acted incredibly bravely, tackling a potentially very dangerous individual who had just moments before indicated to bank staff he was armed."