Welcome to TM Adam. Imperial size fixings on British cars started to fade in the early 1970's being replaced by metric which were already commonplace on European cars. Unfortunately the legacy of the sliding axle front suspension on Morgan's dictated the continued use of imperial size fixings in this and other general chassis and rear suspension areas, continuing to the very end of steel chassis Classic production in 2021. Bottom line you will need both metric for the engine/gearbox and imperial (for elsewhere) spanners and/or sockets to cover your car. There are rare exceptions but an imperial set with A/F (across flat) sizes will cover you for most front and rear suspension using UNF fixings.
Final note the replies that suggest the later Classics had switched to metric fixings exclusively is certainly not the case.
