Portable 30

On the "Winner" and "Portable" series the low voltage is a GB (Grid Bias) tap, not an actual LT (Low Tension filament) cell(s). Though some used with "All Dry" sets from 1939 (e.g. Portable 61) the LT would usually have been rechargeable Lead Acid 2V cell.

Connection is by a socket at each end and flying leads with small plugs for + and - or various taps. None of this series use layer cells / "Biscuits", all use separate cells with connection wiring.

Equivalents: Drydex H1050, GEC BB334, Oldham K540, Siemens 1153

Here you find 204 models, 146 with images and 92 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Ever Ready Co. (GB) Ltd.; London