Sir Keir Starmer will not receive a “blank cheque to do whatever he likes” if Labour win the general election, the boss of the Rail, Maritime and Transport (RMT) union has said.

Mick Lynch said voters had to “grow up a bit” and recognise Sir Keir as the only realistic alternative to the current Government, the removal of which he described as “my number one priority”.

Last week Labour’s shadow Scottish secretary, Ian Murray, challenged Prime Minister Rishi Sunak to put the country “out of this Tory misery” and call a general election now.

Speaking at the War on Want event in central London, Mr Lynch told the PA news agency: “I think Labour have got a good chance of getting elected unless they muck it up, really.

“If you can’t defeat this Government we’ll never get a Labour government again, I would have thought, so he’s got a very good chance of winning.

“That doesn’t mean that we give him carte blanche or a blank cheque to do whatever he likes.”

Mr Lynch said campaigners of “all stripes and identities” needed to form an alliance to ensure that politicians, whether Labour or another UK party, “deliver a working-class agenda going forward”.

I don't give Keir Starmer a free pass, or Rachel Reeves, or anyone else on their front benches – there’s a lot to do, no matter where you look

He continued: “I support getting rid of this Government and I’m a realist – the only government we’re going to get as an alternative will be led by Keir Starmer, so people have to deal with that, people have got to grow up a bit in some senses.

“That’s the government we’re going to get and we have to make the best of that opportunity.”

Mr Lynch said the Conservatives staying in Government would be “a disaster” for working people, the environment and the UK’s international standing, adding: “It’s essential that they go and that’s my number one priority.

“I don’t give Keir Starmer a free pass, or Rachel Reeves, or anyone else on their front benches – there’s a lot to do, no matter where you look.”