Sky News has learnt Mr Allan struck a deal in recent days to offload his interest in J&A Mentoring to co-founder Anna Joseph.

The value of the transaction could not be established on Monday.

Mr Allan, who helped to establish the business in 2018, confirmed he no longer owned a stake in the business, while Ms Joseph said she was "now the sole owner" of the firm.

The former chairman of Britain's biggest supermarket and Barratt Developments, the FTSE-100 housebuilder, relinquished those posts earlier this year after he had allegedly made inappropriate comments towards a number of women during his tenure as president of the CBI, the scandal-hit lobbying group.

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He denied all the allegations other than a remark about one woman's dress suiting her figure, and subsequent investigation found no corroborating evidence for them.

Mr Allan was reinstated to his role as chair of the council of Imperial College London, and has since taken on a number of other advisory roles.

Ms Joseph said that J&A was "doing fantastically well", and now counted 25 FTSE 100 CEOs on its books as clients.

J&A Mentoring business uses a roster of senior boardroom figures including Cressida Hogg, the BAE Systems chair, the Premier League chair Alison Brittain, and Adam Crozier, the BT Group chairman, to mentor up-and-coming managers.

Brian McBride, the CBI president who has spent months battling to secure the survival of the business lobbying group, where Mr Allan was a predecessor, is also listed as a mentor on the J&A website.