Just saw a recent video from Chicago of gas heaters. Are there still any in the UK?
Some still existed in the last years of BR. Not that they were maintained, hence often leaked as much gas as was burned…!
The modern system, as you are no doubt aware, is mains electricity heating. In my area, BR spent a ton of money installing electrical point heating. Then after privatisation, Railtrack renewed all the existing electric point heating (regardless of condition) plus fitted electric point heating at major junctions that had previously been gas.
Only freight only lines (including loops) and some branch line points were left out. Some of these are still not provided with any point heating (although some may have had LPG gas previously).