This Marconiphone advert from May 1950 depicts a picnic and their portable radio.  The radio industry knew that when the weather got warmer, sales of portables went up.  Oddly enough this advert does not state what the dual-purposes are!  The switch-on by the lid opening was a common feature, but as the valves had to warm-up it was hardly immediate.

Summer - time to feature the "Personal Set"

As a prelude to the Summer Season the Marconiphone model P20B is being extensively advertised in the National and Provincial Press as the DUAL-PURPOSE PORTABLE.

As light as a camera, convenient as a handbag, equipped with leather carrying handle this 2-waveband battery receiver, which plays immediately the lid is opened, is the finest and most successful "Personal" Set on the market.

Personal Set Price: £11. 19. 6. plus £2. 11. 11. tax.

Marconiphone: The Greatest Name in Radio

Ref: M.177a.
The Marconiphone Co. Ltd., Hayes, Middlesex.