Gromit: // " The most obvious precedent is the run-up to the 1997 Election. "
I think you mean the 1993 election. Thatcher was removed in 1990, John Major replaced her and the Tories went on to win in 1993. But he led the party to lose the 1997 election. //
I genuinely did mean the 1997 Election, rather than the 1992 one (not 1993), since I had in mind the idea of the Tories getting increasingly associated with sleaze, which distracted from any and all other issues, allowing Labour to win.
As far as the current story is concerned, I'm wondering if the damage is already done: another change of leader mid-election cycle may help a little, of course, but it depends on who that new leader is, and I'm not sure that there are any who can claim to be above the latest scandals. Indeed, everybody in the Cabinet has rallied round the PM, for now, so they can't really claim to be above that which they are currently defending.
The Prime Ministerial Office is bigger than any one person. And, besides, the idea that it's to Johnson particularly and exclusively that we owe our successful* response to Covid is simply false.
*Successful by what metric, anyway?