[Arran]

Rob;
What you had there was what those in the business used to call a "three way" portable, so it could be AC mains operated, DC mains operated, or battery operated. I think I had an RCA portable from the mid 1950s like that, and many Motorola's worked that way, many did not, like the tube Brand Z T.O. sets, those had the tube filaments in series. If you want really elaborate for a portable, G.E manufactured a series of 2 volt "wet cell" radios with a built in AC battery charger, they are VERY heavy though.
Anyhow what I meant by elaborate in battery radios was that there were some high end battery sets that had a TRF amplifier stage, shortwave bands, and a push-pull power output stage, I remember running into one of the Rogers models in one of the books, a console model, that had eight tubes, with four "B" batteries. Most of the time manufacturers would opt for using a vibrator power supply for the more elaborate battery models, even including a magic eye tube, I think there was a Brand Z shutterdial model like that but this Rogers (or Deforest Crosley) ran directly off of batteries, A, B, and C, no magic eye though.
I think I mentioned that Stewart Warner that is in the restoration lineup, it uses four 2 volt battery tubes, but with a 6.3 volt vibrator supply, with a synchronous vibrator. I want to get that working as it's the first battery radio I have had that I could practically use on batteries, specifically a 6 volt sealed lead acid battery, 2 volt battery tubes should be very economical on battery life.
Regards
Arran