Every interception must be authorised by a warrant signed by the home secretary or a minister of equivalent rank.

The sum - mostly for car mileage and 'subsistence allowance' - went to forces chiefs with an equivalent rank of brigadier or higher.

One could imagine an 18th-century notable striding out of a morning, giving orders to the farm staff, then returning inside to greet guests of equivalent rank.

Generally, in most armies and marine units, a lieutenant or equivalent rank leads a platoon, which can consist of three or four squads.

In cavalry companies the equivalent rank was cornet.