Mitter said that his move had been well-planned for years by the entrepreneur in him.

“It’s to do with going outside the law and doing another career,” he said, but declined to give further details, adding only that nothing concrete was planned and that he had several ideas.

After his last day on 30 September Mitter would continue as a “partner emeritus” at ALMT in an advisory capacity but he noted that the firm would remain in “able hands”.

Co-founding partner Sameer Tapia said: “It was a great partnership and wish he had stayed on - he’s been a great friend and a great partner for so many years.

“I wish him well in whatever endeavours he takes on.”

ALMT was founded in London in 1996 by four young lawyers breaking away from making up the acronymic name, of whom Tapia is the only one still within the firm.

Apart from Mitter and Tapia (“M” and “T” in the ALMT name), the “A”, Shalini Agarwal, co-founded Clasis Law one-and-a-half years ago, while the “M”, Manoj Ladwa, started MLS Chase in London 10 years ago and merged into London and regional firm Sherrards Solicitors in February 2012.

Tapia said that although he had no plans to retire at the moment, he hoped the legacy at ALMT would continue, even if all the founders were to be gone one day. “I hope the ALM and T will always be remembered,” he mused.

“[The firm and the other partners] have given me a life and a career, what more can I ask for. It’s my pride and joy.”