When Michel de Carvalho agreed to become the chairman of investment advisory firm Capital Generation Partners in April, the move did not seem to make much sense.

After nearly 50 years in finance, 20 of them at Citigroup, the 73-year-old was reversing a decision to retire for the third time. He handed in his notice from his role as global chairman of Citi Private Bank last Autumn, only for Cap Gen to call him and offer him an office to work out of before giving him the job.