It wasn't the end of Harold Wilson, but for him, in Browning's words, it would never be 'glad, confident morning' again. His image as a dynamic superman had gone forever. Before he lost at the polls in 1970, he had to put up with one more humiliation. In 1969 the government produced a White Paper, In Place Of Strife, which was meant to reduce the incidence of unofficial strikes, but the Trade Unions and Jim Callaghan killed off that proposal, so that Wilson wasn't even left with that consolation. Now, I ought to make it clear that the Wilson government wasn't a period of uniquely dreadful misgovernment, it's just that he'd raised expectations far too high.
Governments are largely the prisoner of events.
In a democracy, governments don't create wonderful new societies, and campaigning isn't the same thing as governing. Campaigning, yes, Wilson could do that, he was a brilliant campaigner, one of the greatest ever, but he wasn't very good at governing, largely because in order to unite his party he pretended that there were easy solutions to difficult problems. It did his reputation appalling damage. Not that the British people ever lost a certain affection for him. They liked his cheeky-chappy image, and they liked his down to earth manner.