Ahmed,

Yes those rifles of yours would be invaluable in the UK, especially in your role as a PH (Squirrels), the grey death of the UK forests is not just an ankle biter but also a neck tearer from above. A good double is a necessity for these DG charges.

I like both the cartridges you mention too. I quite liked using the 5.6x50 (I can't remember if it was rimmed or rimless) in a Frankonia Under and Over double rifle, the first double rifle I ever used - back around 1981 or 82. This one was one barrel on .22 Mag RF and the other in 5.6x50. The .22 Mag barrel was pretty ordinary accuracy, but the 5.6x50 was a three shot one hole killer.

The hornet rook rifle sounds like it will also be very handy and a dream to shoot.