Theresa May says it would be ‘catastrophic’ to cancel Brexit. Is she right?

The prime minister will tomorrow make a powerful speech – in the heart of Brexit UK, Stoke on Trent – that MPs ‘all have a duty to implement the result of the referendum’, because failure to do so would wreak ‘catastrophic harm’ on ‘people’s faith in the democratic process and their politicians’.

Coming as it does from the most important and powerful elected politician in the UK, this dramatic claim is worthy of careful consideration. What is it based upon?

Well it is founded on the premise, in her words, that ‘on the rare occasions when Parliament puts a question to the British people directly we have always understood that their response carries a profound significance’.

That is an uncontroversial statement – though it is worth adding the rider that under the UK’s unwritten constitution, referendums have ‘advisory’ status, they do not mandate governments or parliament in a binding way.

But May also points out that when her predecessor David Cameron wrote to voters just before the referendum campaigns began, he said ‘this is your decision; the government will implement what you decide’.