> The forced changeover from coal gas to natural gas is largely credited with a reduction of suicide by 40% after it was done.

The mechanism of that reduction very well could be reducing the level of depression in the populace and thus suicidal ideation, rather than just making the means less handy (or of course, some combination). Coal gas, like any other gas used for combustion, doesn't burn perfectly and UK homes likely had persistent amounts of carbon monoxide roughly all the time since heat gets used not-quite-year-round.

From https://en.wikipedia.org/wiki/Carbon_monoxide_poisoning#Chro... :

> Chronic exposure to relatively low levels of carbon monoxide may cause persistent headaches, [...], depression [...].