"Andrew Turnbull has always had strong opinions about Gordon Brown, but he's only ever expressed them in private. Today he is saying that he thought he was speaking off the record to the Financial Times.

"I understand that he agreed to speak to the FT in connection with a piece that they are planning for Thursday on how Gordon Brown has changed the Treasury and he thought that chat would be off the record. He has now found, to his surprise, that it was not.

"That does not change the fact that he said it, but does mean it's not quite as serious a breach of civil service etiquette. He just seems to be the latest senior civil servant or politican who has not got the terms clear before speaking to a journalist. I understand the BBC spoke to him this morning and the reply was: 'I think I've done enough damage already.'

"It's a huge embarrassment for Gordon Brown - a damaging one too - and an absolute gift for the Conservatives. I imagine David Cameron and George Osborne will be rubbing their hands in glee at this coming just the day before the Budget. Andrew Turnbull has now written their script for them, although the irony is that he thought it was a private conversation.

"I've spoken to various ministers today and some think it's hilarious - a bit too close to the truth. The general feeling is that Gordon Brown's best bet is to laugh it off in tomorrow's Budget speech. I have no doubt that he'll already have his scriptwriters working on the best joke they can come up with."

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