the Beaufighter II with the Merlin engines was a nasty aeroplane which was underpowered
The pilot notes would give the impression that ALL Beaus were nasty aeroplanes. So unstable were they that the notes recommend that cloud or night flying not be indulged in, and that also applied to those fitted with the dihedral tailplane, which was meant to increase stability. Yet they was used as a night fighters. Oddly, crews of the night fighter preferred the more unstable flat tailplane.
All the Merlin production (450, not including 2 prototypes) were built as night fighters, and served first with 600, 406 and 205 Squadrons. The Merlin was introduced in fear of the Hercules production being too stretched for the bombers. While the Merlin only gave 1,250 HP v Hercules 1,400 HP Mk.IF, on take off, the Merlin gave more at altitude. The Hercules finally ended with a rating of 1,735 HP.
The unbuilt Mk. IV with a proposed slim fuselage and Griffon engines would have been something to see.