The former NatWest chief executive breached data rules when sharing details about Nigel Farage’s banking, the information watchdog has ruled.

The Information Commissioner’s Office (ICO) said there were two privacy breaches involved in Dame Alison Rose’s disclosure to BBC News business editor Simon Jack.

This enabled him to report Mr Farage no longer met the financial criteria to hold an account with Coutts, which is part of the NatWest Group.

The ICO judged her actions were “unacceptable” – but no further regulatory action was needed as she already resigned and NatWest – partly owned by the government – is conducting its own investigation.

A NatWest spokesperson said: “We fully co-operate with the ICO in its assessment of any customer complaint, but it would not be appropriate for us to comment on this individual case.”

Coutts requires account holders to have at least £1m in investments or borrowings, or £3m in savings.

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Dame Alison said she believed it was public knowledge Mr Farage was a Coutts customer and had been offered a NatWest account but did say she made a “serious error of judgment”.

She said she repeated the Coutts stance – which Mr Farage had publicised – that the bank saw the account closures as a commercial decision.

An ICO statement said, “we found that an individual employed by NatWest shared information when they should not have done, and that by doing so they infringed the complainant’s data protection rights”.

Chancellor Jeremy Hunt said in July, before Dame Alison resigned that he had “significant concerns” about how she handled the closure of the accounts.

NatWest is due to release financial results on Friday and is preparing to cancel bonuses and share awards owed to Dame Alison following her departure.

She’s eligible to be considered for a pro rata portion of the £2.9m annual bonus and long-term share awards that made up the remainder of her total maximum pay package of £5.3m.

Mr Farage told the Financial Times, “The ICO report confirms that Dame Alison Rose was in breach of data rules, of the FCA rule book and oversaw a culture of deep political prejudice at NatWest.”