Smash-and-grab raiders let off a smoke flare in a £30,000 jewellery robbery.

Staff at WE Clark jewellers in Cliffe High Street, Lewes, were stunned as the shop filled with smoke yesterday afternoon.

One robber smashed a glass counter as the other kept an eye on the staff.

The offenders grabbed a diamond necklace worth £30,000 and fled down a twitten by the River Ouse, at the rear of an NCP car park.

They escaped on a high-powered Yamaha motorbike.

The shop owner's son, David Clark, 21, was walking to the shop when the robbers ran past him.

He ran into the jewellers as the flare began catching part of the shop alight.

Mr Clark and shop assistant Daniel Blackford, 20, used extinguishers to douse the flames.

The owner, John Clark, 53, was out at the time. He said: "The fire was taking hold and thanks to their presence of mind a serious blaze was avoided."

He said the two and another assistant, Tina Call, were unhurt but shaken.

It was just before 2pm when the two men entered the 180-year-old business, which has a shop either side of the river. The Clark family has owned it since 1919.

The pair went into the east-side shop and made straight for the necklace. Police believe they may have stolen to order.

One robber is about 40, 5ft 5in, with long, greying hair and slightly balding. He wore a dark baseball cap and dark clothing.

The other is about 20, 5ft 10in with messy hair and a tanned complexion. He wore a dark blue jumper, dark jeans and white trainers.

Anyone who can help should call Sussex Police on 0845 6070999 or Crimestoppers on 0800 555111.