Preston jeweller George Banks was broken into in the early hours of Monday morning, with the thief fleeing with around £100,000 worth of jewellery.
It is believed that the man used power tools to break into the premises through the wall of the adjoining bar, the Plug and Taps.
This took place at around 4:30am, and police were alerted at 4:45am, however it took the offender no more than five minutes to break into a number of jewellery cabinets before fleeing with his loot.
Detective constable Mark Thornton, Preston CID, said: “An investigation has been launched after a major theft from a jewellers in Preston.
“It is believed at this stage that a man has broken into the building after smashing through the adjoining wall of Plug and Taps using power tools.
“The offender has then broken into a number of display units stealing a substantial amount of jewellery before making off from the scene a short time later.
“We are particularly keen to speak to anyone who knows what happened, or saw someone in the area around the time of the offence acting suspiciously.
“Furthermore if you know someone who has come into possession of a large amount of jewellery, or you have today been offered a large amount of jewellery for sale, then call police immediately.”
An investigation is underway after more than £100,000 of jewellery was stolen following a burglary in Preston today (Monday, October 5).
Police were called around 4.45am to reports of a burglary at Banks Jewellers in Lune Street.https://t.co/L75VAgURdl pic.twitter.com/6Vp4BfuNjn
— Lancashire Police (@LancsPolice) October 5, 2020