Faster and more powerful than their predecessors and equipped with a ramp to load/offload 16 commandos in full battle rig, they were almost exclusively designed for operating over land.

It's the ability to fold the tail section - it's been completely rebuilt for the Mk4 - and the rotor heads which assist flying from Royal Navy carriers in particular.

This first Mk4 made its debut in the Somerset skies last autumn, but it took nearly a year for the Leonardo team to make the short hop to Yeovilton, where it dropped in to refuel as the air station prepared for its annual air day.

At the controls, aircraft captain Rob Dowdell, Leonardo's senior test pilot, with QinetiQ test pilot Lt Ian Pearson at his side in the cockpit and Leonardo's flight test engineers John Doherty and Simon Lewis in the back of the cab.

The first of 25 Mk4s will be handed over to CHF in January, with transition to the new machine completed by the end of 2020.