A Rolex thief punched a shop assistant before stealing two high value watches.
The man, who came into the shop wearing a watch made by the Swiss manufacturer, snatched another two from inside a branch of Cash Converters in Accrington town centre.
Detectives said he struck the shop worker as he was being shown the watches, which were worth a total of more than £6,000.
A CCTV image of the man, who ran away towards the Eastgate bypass following the robbery, has been released to help trace him.
Sergeant Eric Halford, of Hyndburn CID, said the robber entered Cash Converters on Broadway at around 11.40am on Friday, May 11.
He said: “He asked to view two high value watches – a Rolex Oyster Perpetual and a Breitling Crosswind.
“Once presented with the watches the offender struck the shop assistant, snatched the watches and ran from the store towards the Eastgate bypass in Accrington.”
The robber is described as being black, approximately 35 years old, of medium build, 5ft 10in and spoke with a southern accent.
He was wearing smart clothing, possibly a dark waterproof or tweed type jacket, possibly with a flat cap and had a Rolex watch on at the time of the offence.
Wayne Greet, area manager at Cash Converters, said he was shocked by Friday’s event.
He said: “Fortunately the member of staff involved wasn’t badly hurt during the robbery.
“This thief was opportune and used force to snatch the items and leave the store.”
Anyone with any information can contact Accrington Police or Lancashire Constabulary on 101 or contact DS Eric Halford on 01254 353742.
Alternatively, contact the charity Crimestoppers anonymously on 0800 555 111.
The Rolex Oyster Perpetual has a serial no. M969879 and the Breitling Crosswind, serial no. A13355.
