Rolls Radio Transistogram

[Mike Watterson]

It isn't in those EMI hybrid sets, for whatever reason... perhaps one factor was that a 3V rather than 4.5V LT supply wouldn't have been as suitable for the OC72s?

I see what you mean. Perhaps they had a load of DAF96 in stock, or it was still cheaper than a transistor and diode. Or your theory that they needed 4.5V anyway is correct.
https://www.radiomuseum.org/r/marconi_ma..._60_b.html

Is RM incorrectly listing 1.5V rather than 4.5V battery?

I see the HMV is listed with 4.5V
https://www.radiomuseum.org/r/hismasters...410_g.html

I presume the two sets only differ in badge?

EDIT:
I've suggested on RM org that the 1,5V is a mistake.