When Labour came into power in 1974, they did so with a strengthened commitment to Home Rule for Scotland
“The classic nationalist scenario, that of heightened expectations punctured by reality.”
https://open.substack.com/pub/jackie125/p/the-movement-for-self-goverment-for
The Labour government accepted demands from a rebel group for a referendum. That was seen as a delaying tactic but not a catastrophe
But as the Bill went through the Commons George Cunningham an expat Scot who represented Islington, inserted an amendment ruling that 40% of the electorate had to vote yes - not of the votes, the electorate. So people who were dead or had the left the country or who never voted were to be counted as supporting the status quo. This was obviously an unreachable bar. This sucked air out of the movement.