There was very little the recruitment agency that supplied one of the men convicted of Britain's biggest robbery could have done to stop him being employed, despite a police caution for shoplifting, according to employee-screening experts.

Emir Hysenaj is reported to have been supplied by Crowborough recruiter Beacon Contract Services to work at the Tonbridge depot of Securitas in December 2005, two months before the £53m heist.

David Chernick, who leads Reed Screening, told Recruiter: "It's very hard to see how either the employer or the agency could have justified doing a CRB check because his job doesn't appear to fall into one of the categories that allow you to look at their criminal history. And in any case, these checks can take 12 weeks to complete."

Alexandra Kelly, a director of Powerchex, told Recruiter: "There was nothing they could have done. The most stringent of criminal checks is reserved for people who are one-to-one with children or working with vulnerable adults, not for those in regular jobs."

However, Kelly said there were ways of reducing the risk. "If the caution had been during previous employment, it would have made sense to talk to the previous employer, or do a character reference check, because for something like that people would have heard."

A spokesperson for Loomis, the rebranded cash-in-transit part of Securitas, which used to own the Tonbridge site, told Recruiter that at the time of the robbery Securitas used agencies to screen candidates, but that the company now did these in-house.

"Tonbridge was a factor in that it made them look at all their arrangements very carefully, but it wasn't the sole reason," he added.

Beacon Contract Services declined to comment.