A controversial aide to the Education Secretary, Michael Gove, faces questions over a potential breach of the code of conduct for ministers' special advisers after he implied that a journalist required therapy.
Dominic Cummings delivered the jibe in an email protesting about reports describing the sometimes heavy-handed methods adopted by special advisers in the Department for Education.
The remark was aimed at Chris Cook, the former education correspondent of the Financial Times who has been involved in a long wrangle with Mr Gove about ministers' use of private email accounts for government business.
Mr Cummings made the comment in an angry message to The Independent's education editor, Richard Garner. He criticised a comment article written by Garner and told him he should "speak to Chris Cook about a good therapist".
The code governing the conduct of ministers' special advisers ("spads") places strict limits on their activity, including the instruction to avoid "personal attacks".
After The Independent's story last week, published on Friday night, Mr Cummings fired off an email to Garner, mocking his aside that he had recently suffered the "wrath" of DfE advisers.
Mr Cummings then accused the journalist of a "comically unprofessional attempted hit job with a breathless conclusion about feeling the 'wrath' of a spad – by implication obviously me".
He added: "My only contact with you last week was, as you know, my PS in an email to someone else.
"Either a) you really think that counts as 'wrath', in which case you shd speak to Chris Cook about a good therapist, or b) you know it's absurd but were ordered to write something about spads and that's the best you could do because you know I never call and shout at you."
The ministerial advisers' code says that special advisers must not take public part in political controversy and must "express comment with moderation, avoiding personal attacks".
Asked about the email, Mr Cummings said: "The Independent seems to be on a kamikaze mission to go bust as fast as possible by writing ludicrous and dishonest stories."
Mr Cook, who declined to comment, first attracted the Education Department's ire 18 months ago when he disclosed Mr Gove used an email account in his wife's name to correspondent about government business, making it harder to scrutinise under Freedom of Information laws. Mr Gove has been instructed by the Information Commissioner to release details of emails from private accounts.
Mr Cummings is embroiled in a separate controversy after a complaint by Labour that he and another adviser, Henry de Zoete, flouted their code of conduct in postings on the Twitter feed @toryeducation attacking journalists and critics of government policy. The Twitter feed accused Mr Cook of being a Walter Mitty-type character. Mr Cummings and Mr de Zoete admitted contributing to the feed, but have said they were "not @toryeducation".
In opposition Mr Cummings was a trusted aide to Mr Gove. But after the election his appointment to a post in Government was blocked by Andy Coulson, David Cameron's communications director. Mr Coulson suspected Mr Cummings of leaking details of a private meeting. Mr Cummings was brought into the department after Mr Coulson was forced to resign by the phone-hacking scandal.
Dominic Cummings: The offending email
From Dominic Cummings
To Richard Garner
You've written a piece as part of a comically unprofessional attempted hit job with a breathless conclusion about feeling 'the wrath' of a spad – by implication obviously me. My only contact with you last week was, as you know, my P.S. in an email to someone else. Either a) you really think that counts as 'wrath', in which case you shd speak to Chris Cook about a good therapist, or b) you know it's absurd but were ordered to write something about spads and that's the best you could do because you know I never call and shout at you... I will be circulating my email to your colleagues so they know exactly what is behind your 'wrath' column.