That one is probably made by LEAK who were also owned by RANK at that time and were manufacturing in England.
This thread at Classic Speaker Pages has photos of the internals and a couple of the PCB's are marked LEAK.
I received yesterday this nice NOS condition Wharfedale Linton amplifier. Carton has been opened, but amplifier with tags is still wrapped in plastic. Speaker leads supplied with amp do have tags attached and shorting plugs are in plastic bag. Wharfedale did not produce their own amplifiers. As L...
community.classicspeakerpages.net
The Linton Receivers and later units may have been made by Rotel but the pictured amp is a Leak Delta 30
This thread has a photo of the internals of the Delta 30
My earliest memory of my Dads hifi setup included a Leak Delta 30/70 (neither Dad or I can remember which) amplifier hooked up to a gigantic pair of Goodmans Magnums. About 10 years ago I got myself a full Leak setup, to include a Delta tuner, Leak sandwich speakers (600 series 8ohm) and hooked...
audiokarma.org