Burnham would be a decent shout.
But I don't think it matters who the leader of the opposition is at the moment, the Tories are absolutely teflon with getting Brexit 'done' and the vaccine bounce. All the other shit they’re up to people either don't care about or are oblivious too.
I’m sure Starmer (or whoever the LOTO was) would love to come out on the attack and call Johnson a useless lazy fuckwit, we know that’s what he thinks of him, but it’s not what the public wants to hear right now. Criticising Johnson is tantamount to treason in the eyes of many.
Instead he just has to bide his time and play the long game. It makes him look weak or indecisive or ineffective but it’s his best bet. It’s too early to come out on the attack now, so far from the next election. Bide his time, wait for the inquiries into Covid/PPE/Corruption to come out, wait for the Tory infighting to start, and then go on the offensive.