I am indebted to Daniel Barnet for highlighting the following from the Court of Appeal. Follow the link for the full ruling.
Does requiring a security guard to remain on call during his rest breaks contravene the requirements of the Working Time Regulations? Not necessarily, according to the Court of Appeal in Hughes v The Corps of Commissionaires Management Ltd.
Regulation 12 provides that a worker is entitled to an uninterrupted 20 minute rest break when his daily working time is more than 6 hours. Regulation 21 excludes that requirement where the worker "is engaged in security and surveillance activities requiring a permanent presence...", but Regulation 24 provides that an employer should "wherever possible allow him to take an equivalent period of compensatory rest".
The security guard in this case was provided with an area where rests could be taken, but he had to remain on call during those periods, meaning that his break might be interrupted. Significantly, if that happened he was permitted to start his break again.
The Court of Appeal held that the employee's work fell within Regulation 21, and that the breaks provided to him were properly described as an "equivalent period of compensatory rest" (Regulation 24). The employee's suggestion that a risk assessment might be required because of the possibility of interruption was firmly rejected, the Court noting that he might well end up with a break longer than the 20 minutes typically required by the Regulations.