The first and most serious offence was at the Cheltenham and Gloucester Building Society in Church Walk, Burgess Hill.

Three women staff members were in the branch when a man walked in and pulled a gun.

He was given money by one cashier but complained about the small amount and another cashier opened a second till and gave him several thousand pounds.

DC Chris Smith, of Haywards Heath CID, said all the staff were traumatised by their ordeal.

He said: "The man said to the first cashier 'Is that it?' at which point another till was opened.

"The first cashier is genuinely in a state about it, not surprisingly. As far as we can tell the gun was real and was pointed at her.

"She was absolutely terrified and is still coming to terms with it, as are the other two members of staff who were on duty."

The robber, dressed in a fluorescent jacket over a hoodie and wearing white latex gloves, had a black fabric case strapped over his shoulder and was carrying a broom.

Moments before the robbery staff had seen him pretending to sweep in the alleyway beside the premises and when he went in he propped the door open with the broom.

As he left he snatched the broom, carrying it with him and ran down the alleyway where he was joined by an accomplice waiting by the Cyprus Road car park.

Both men ran through the car park to the far side and into Middle Way where they were seen to get into a new-looking black Vauxhall Corsa and drive off.

The previous day the building society staff had called police when they because suspicious about two men who were hanging around outside the branch.

DC Smith said: "There must be a lot of people who saw one or both of these men at some point either as the robbery was occurring, just before or just after, or the previous day. We have CCTV footage of the robber in the branch but we would appeal for more witnesses to come forward to assist us who saw he and his accomplice at other times."
The robber with the gun was dressed distinctively with a sleeveless high visibility fluorescent v-necked jacket over a dark hoodie, with the white gloves, dark trousers and old trainers and carrying the bag and the broom. He was about 5ft 7in tall, stocky, estimated to weigh about 12 or 13 stone, and with three or four days dark or black stubble.
The second man has been described as between 20 and 25 years, 5ft 8in to 6ft tall and with a lean build and spiky black hair. he wore a black hoodie or tracksuit top and black tracksuit trousers with white trainers.

Anyone with information should call Haywards Heath CID on 0845 60 70 999 quoting serial 1240 of June 18, or call Crimestoppers anonymously on 0800 555 111.