With a bone in her teeth HMS Illustrious, or “Lusty” as she is known in the Royal Navy, steamed out of Falmouth Bay on Monday after spending six hours at anchor operating with helicopters from RNAS Culdrose.

Onboard Illustrious are the Royal Navy’s new Merlin submarine-hunting helicopters which will face their greatest test yet when they head into the Atlantic in the biggest exercise of its kind for many years.

Taking part in Exercise Deep Blue, in the Western Approaches, the nine Merlin helicopters will practice skills which were once the mainstay of the Royal Navy’s aircraft carrier operations.

After a week and a half’s training around the UK by day and night, HMS Illustrious and her helicopters will move out into the expanse of the Atlantic for Deep Blue itself, which reaches its climax in mid to late June.

It is the first time the latest version of the Merlin – the Mk2 – has been tested en masse. After more than a decade on the front line, the Merlin fleet – based at Royal Naval Air Station Culdrose in Helston – is in the midst of a £750 million revamp which will help to keep them at the forefront of naval warfare until the end of the 2020s.

The Merlin Force will spearhead Exercise Deep Blue, with nine new Mk2s onboard the Portsmouth-based carrier – the largest concentration of submarine-hunting helicopters in recent memory, and the largest ever concentration of Merlins at sea.

Illustrious is the UK’s High Readiness Helicopter and Commando Carrier and is primed to fulfil multiple tasking as demanded by higher authority. Along with the landing platform docks the helicopter carrier deploys as part of the UK’s Response Force Task Group.