Four men wearing masks and armed with crowbars entered St Neots Emporium in Fishers Yard just after 11am on 23 December.
They threatened two female members of staff before making off with valuables worth tens of thousands of pounds.
The men left in a light grey coloured Ford Fiesta.
PC Zoe Bramley, from the Southern Acquisitive Crime Team, who is investigating, said: “We would like to hear from anyone who may have been in the area at the time and saw these four individuals in the moments leading up to the robbery or perhaps saw the vehicle they left in.
“If anyone has any CCTV footage or dashcam footage showing the individuals or the vehicle, we urge them to come forward.”
Anyone with information is asked to contact police online www.cambs.police.uk/report quoting reference 35/92827/22.
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