Henry Zeffman: Early release of Budget details is totally surreal

This is totally surreal.

Keir Starmer and Kemi Badenoch have gone through the motions of a Prime Minister's Question session before the Budget.

In response to questions from the Conservative leader, the prime minister said that it's "literally 25 minutes" until the measures will be unveiled.

Not so.

The Budget is already out there, thanks to the Office for Budget Responsibility, which has published the details in error.

Its economic forecast appeared on its website unexpectedly early.

It caused a buzz in the Commons chamber.

Multiple Conservative MPs were going through the OBR documents and graphs on their phones.

Reeves had been looking at her own phone, and notes were being passed down the row of cabinet ministers.

Now the Office for Budget Responsibility has apologised and launched an investigation.

It describes the blunder as a "technical error".

It said it has now been removed, adding: "We apologise for this technical error and have initiated an investigation into how this happened.

"We will be reporting to our oversight board, the Treasury, and the Commons Treasury Committee on how this happened, and we will make sure this does not happen again.

"Our economic and fiscal outlook and supporting documents will be released when the Chancellor has finished her speech."

The report appears to confirm a number of measures which were expected to be included in the Budget, including the end of the two child benefit cap, the extension of income tax threshold freezes for another three years and a new mileage based charge on electric vehicles.

But it is truly extraordinary. An hour ago, it would have been unimaginable.

It's hard to find the right adjectives to do it justice.

There will be total fury at the top of government right now and, presumably, a reckoning of some sort for the OBR.