Sir Brian hold a substantial part of his wealth within Souter Investments Limited, of which he is the co-founder. That includes a 16% shareholding in Stagecoach.

According to the firm’s latest strategic report, Souter Investments Limited posted a profit of more than £40m.

For the year ending March 31 2021, the group made a pre-tax profit of £42.9m. That marks a 145% increase on the 2019 figure as Souter Investments Limited posted a £95m pre-tax loss.

The results mark a return to the figures posted in 2019 when the investment firm recorded profits of £80m.

Director Calum Cusiter said an increase in the price of the Stagecoach shares had a “major impact”. He said: “The group’s quoted investments are valued at £120m. The group’s largest single investment held is the 87 million shares in Stagecoach, which were valued at £87m.”

That is a £27m rise from the 2020 valuation of the bus firm.

Souter Investments Limited holds stakes in around 25 firms, with a typical investment of between £5m and £15m. The value of the other investments also rose to £183m. Net assets also rose by 11% during the year reaching £329m, up from £295m last year.

Mr Cusiter added: “The generation of new opportunities was again strong during the year. We continue to be rigorous in our selection of investments.

“We continue to diversify our portfolio and retain a healthy appetite for unlisted investments. The results for the year were positively impacted by a partial reversal of the year prior drop in the Stagecoach share price, together with net increases in the value of other investments.”