Two raiders who took part in a terrifying early morning supermarket robbery in which a female shop assistant was punched in the face have been jailed for more than 13 years.

The masked men lay in wait in a ceiling cavity inside the Co-op store in Queenborough and then dropped down from their hiding place to confront the employee as she arrived for work just after 5.40am on September 13 last year.

Christine Adams was at her locker when the raiders, wearing balaclavas and dressed in black, leapt from a loft hatch and demanded the safe keys.

One was armed with a screwdriver, Maidstone Crown Court was told, and they fled with more than £5,500 in cash.

The two 'inside men' were Reece Whiting and either Ricky Chambers or his cousin Michael Chambers. A jury was told it did not matter which of the Chambers men was in the store as the other was waiting outside, communicating when to strike.

Whiting, 25, of James Street, Sheerness, and Ricky Chambers, 27, of Cliff View Gardens, Warden, both denied conspiracy to rob at the start of their trial on Monday.

But they changed their pleas to guilty and were each jailed for six years and eight months on Tuesday.

Michael Chambers, 31, from Thornton Heath, Croydon, admitted the same charge at an earlier hearing.

Described by a judge as "a ruthless criminal", he is currently serving 16 years for his involvement in the robbery, as well as a violent burglary in Gravesend and several other raids across Kent.

Prosecutor Patrick Dennis told the court Ms Adams was punched when she refused to hand over the safe keys.

Having been knocked to the floor by the "considerable" force of the blow, she met their demands.

Despite the violence meted out, Ms Adams tried to call police using her phone. But the raiders spotted her before she managed to raise the alarm.

She later told police how she was frightened and left traumatised by her ordeal, which she described as "the worst incident" in her 21 years' employment.

The robbers escaped in a stolen VW Polo which was later found burnt out four miles away, the gang having transferred to a Ford Mondeo.

Ricky Chambers, known as Lee-boy, was arrested four hours later. Police found £1,000 in notes under his car passenger seat and £941 in coins in the boot.

DNA on a crowbar found in the loft hatch was matched to Whiting. Other evidence linking the robbers included CCTV, automatic number plate recognition cameras and mobile phone data.

Mr Dennis told the court: "This was a well-planned, targeted robbery and the defendants, together with Michael Chambers, agreed for this robbery to be carried out, all playing different roles."

Bill Taylor, 27, and Ricky Chambers's partner Cally Oswell, 30, both of Cliff View Gardens, Warden, were also charged with conspiracy to rob.

It was alleged Mr Taylor was the Mondeo getaway driver and that Ms Oswell was involved in the raid's planning.

However Judge Adele Williams instructed the jury to return not guilty verdicts after the prosecution offered no evidence.