I came across this article where twelve pairs of loppers are reviewed. They named the Gardena 500 BL Ultra Light Comfort Bypass Loppers as their best buy with a score of 18/20.

They seem to be reasonably widely available with Tooled-up having them in stock at £25.95 at the time of writing.

Tooled-up also stock the runner up pruners that scored 17/20, the Fiskars L78 Large PowerGear Bypass Loppers.