'Golden Knight' branded equipment was manufactured by Radio (1936) Ltd, they were distributed by Farmers Trading Co. Ltd. Currently there are 33 documented models.
Golden Knight was a brand of Farmers / Calder McKay. They had several different manufacturers, although the main one was Radio Ltd - meaning a lot of Golden Knight radios look very similar to Ultimate, Rolls, Skyscraper etc and equivalent models shared the same chassis. The other main manufacturer appears to have been Westco.
Where the model code is not clearly stated it can be found (in most cases) as the letters at the start of the serial number. For example, RB10574 would be a model RB.