Having finished restoring an Ever Ready Sky Baronet portable, I started on a Sky Countess for what I thought would be a change. Looking at the PCB and thinking this looks familiar I loaded No2 of Paul Stennings excellent circuit CDs only to be directed to ERT Service Sheet, 1163 for both sets
I knew that the Sky Baronet was electrically similar to the Berec Matador but was suprised that the Sky Countess was the same as well.
I suppose by 1958 most of the design effort would have been focussed on transistor models