Not too far off, given the nature of the fire. Gas for carriage lighting in those times was coal gas, the same as in domestic supplies of the era, which was distributed from railway gasworks in specific wagons - the GWR version had what looked like about 10 large barrels, mounted sideways in a strong open frame. Propane (modern Calor Gas etc) came later.
And the last BR gas-lit vehicles i believe were the Glyncorrwg miners train in South Wales, which combined all of last on BR of passenger wooden seats, 4-wheels and gas-lit. It was retained until the early 1960s, hauled by a 57xx tank loco, because the very inaccessible colliery had no pithead baths until then, so miners returned "dirty" at the end of shift. The Hemyock coach, onetime Barry railway, described above, was condemned in the mid-1950s, not because of its gas lighting but due to structural deterioration of the wooden body.