Police are appealing for any Dash Cam video footage from motorists who were travelling on the A346 between Swindon and Marlborough between 09:00 and 10:00 on Monday 23 July.
At approximately 09:45 on Monday 23 July, a woman was walking along Marlborough High Street towards the Post Office to cash in the weekend takings from her place of work.
As she was walking through the area of The Parade, a man ran up to her from behind, grabbed the bag of cash which amounted to several thousands of pounds, and made off towards the High Street.
The man was chased on foot by a member of the public in the direction of The Green, but he got into a silver Vauxhall Astra van and made off towards Swindon.
The man was wearing all black clothing and a motorcycle helmet. It is believed a GSXR 1000cc motorbike was also involved in the theft.
Two men, aged 26 and 28, from Swindon, have been arrested on suspicion of conspiring to steal from a shop. Both have been released under investigation while enquiries continue.
PC Nick Spargo said: “I am really keen to speak to anyone who may have been travelling between Swindon and Marlborough on the A346 between 9am and 10am on 23 July in both directions who may have a dash-cam fitted to their vehicle, and anyone who may have been in the County Way area of Swindon from 10am with dash-cam footage.
“Anyone with information should call police on 101 or Crimestoppers anonymously on 0800 555 111.”