I'm just wondering if anywhere in the UK was still DC by the time TV arrived? If so, a tiny minority of likely sales. My home town of Aberdeen changed from DC to AC in the 1930s, and it was getting on for 20 years before TV got that far.
ISTR some hybrid sets - part valve part transistor - that still used a dropper for the valve side, but a more normal transformer for the low volts transistor side.