A six-strong group of women and children stole more than £800 of stock from WHSmith in Twickenham last month.
The theft saw three adult women, one girl and two children sneak around the store, picking up masses of expensive stock.
The group, suspected to be members of the same family, ran from the store after being spotted by the staff.
The two children involved were believed by staff to be under ten-years-old.
A store spokesman said: “They came in really sneakily, began sticking items down their trousers, putting expensive stock in their pockets.
“They were having a field day.”
Staff said the incident on King Street seemed organised, as the gang of thieves entered the store and quickly dispersed between various aisles.
The store spokesman added: “It was a bit of a shock, especially with the fact they had kids. It’s ridiculous to let the children believe it’s okay to do that.”
Scotland Yard said: “On Tuesday 19th September at approximately 13:30, three adult females accompanied by two girls and one boy, stole between £150 and £200 of items from WHSmith, King Street, Twickenham.
“On being seen by staff, the group ran off.
“An investigation is ongoing. No arrests have been made.”
An initial crime report to the police estimated the stolen goods were worth more than £150 but after a stock take WHSmith now believes the sum to have risen to more than £800.
Store staff said the three adult females all wore similar fur bodywarmers, which made them stand out.
Anyone with information should call police on non-emergency number 101 or visit the police website.