Armoured tracked vehicles had been driving at up to 40 mph since 1977 . But it emerged in 2013 they were not exempt from tracked vehicle laws . Limit was then halved to 40 mph , but government now wants to reduce it to 40 mph . experts believe 20 mph limit is causing congestion and health concerns .
Armoured tracked vehicles had been driving at up to 40mph since 1977 . But it emerged in 2013 they were not exempt from tracked vehicle laws . Limit was then halved to 20mph , but DfT now wants to raise it to 40mph . Ministers believe 20mph limit is causing congestion and health concerns .