I did wonder whether she might be positioning herself as the Queen Across the Water for a future strike against Johnson and his cabal.
More likely, her ambition, dimmed as it might be for now, could no longer trump the idiocy she was having to go along with.
There's certainly a constituency of disaffected Tories out there who might be attracted by the prospect. Some may jump to the Lib Dems, but they're a poor imitation. The independent group (whatever it's calling itself now, I can't keep up) is still staggering along and attracting a few despite being barely a statistical blip in the polls. For all the applauding whenever a Tory jumps ship to them, it does mean that the Lib Dems' numbers now include some rather unsavoury characters whose pasts can't be glossed over by any claims of a change of heart.
If it does happen, the country and the party will totally have wasted the years since Thatcher and Major at the cost of the desperate attempts to paper over the cracks between the "wets" and the "dries" (in the Thatcher era), the One Nationers and the hardline nutters (Major's "bastards" ), and the Europhiles and Eurosceptics from the Cameron era onward. And let's not fool ourselves that for many of them, Euroscepticism isn't a proxy for some barkingly rightwing stances on other issues.
Rudd is still a horrible politician who's enacted some terrible, heartless policies, of course. The fact she appears to have some principles and is on the right side on these current issues shouldn't mask that. The same could be said about Jo Swinson, whose record in the coalition was shameful.