In reply to lone:
I don't think Mrs T would have done any better. I suspect she was probably too savvy to get into this kind of mess in the first place.
The Brexit disaster hasn't come about because Theresa May is incompetent. It's merely the logical conclusion of setting up two parallel systems of democracy that aren't aligned (perhaps that makes them not parallel?). There's the direct democracy of the referendum which wanted Brexit (by a whisker); and the representative democracy that thinks it's a shit idea.
May has decided to try to take the direct democracy seriously, yet she doesn't want to drive the economy off a cliff. So she's attempting to achieve mutually incompatible aims.
I suppose you could argue that this is in itself incompetence, but what are her options? Ignore the vote (national political unrest and personal political suicide) or drive the economy off a cliff (national political unrest and personal political suicide)?
A bit more detail on how the UK's "negotiating position" is to demand incompatible aims: