Police would like to speak to the man pictured.
The bookmakers, in Station Lane, was targeted at around 9.30pm on Tuesday, 14 May.
Two people walked into the shop and demanded cash from staff.
Investigators say one of the suspects “threatened them (staff) with an item which was brandished as if it was a firearm.”
The two men made off with a large amount of cash. They left and headed off in the Rainham direction.
A Met Police spokesperson said: “No staff member was hurt in the incident.”
Police are releasing images of the two suspects, which were captured on CCTV at William Hill.
Anyone with information as to the identity of the two men should call the Flying Squad East on 020 8345 4221 quoting reference 7626/14May19.
To remain anonymous, call Crimestoppers on 0800 555 111.
Tags: Havering, Rainham, Hornchurch