A total of 19 Mk3 and six Mk3a Commando Merlin helicopters have now been upgraded to the Mk4/4a standard, with the work overseen by the procurement arm of the Ministry of Defence (MoD), Defence ...

The UK has upgraded 25 land-roled Merlin HC3/3a helicopters to the maritime Commando Merlin HC4/4a standard, of which 24 remain in service following the accidental loss of one airframe in 2024.