Marks & Spencer’s chief financial officer has quit weeks after it was announced the firm would drop out of the FTSE 100 for the first time.

The company announced Humphrey Singer’s departure on Saturday, although his leaving date has not yet been decided.

Mr Singer, who joined M&S last year, said it is “the right time to move on”.

He added: “I feel privileged to be a part of the challenging but hugely rewarding turnaround at Marks & Spencer.

“It is a brilliant business and a much-loved brand for our colleagues and our customers.

“The transformation taking place is of a scale, depth and pace not seen before at the company.”

M&S chief executive Steve Rowe said: “Humphrey has been a huge asset to the business.

“He has helped to establish the foundations of our transformation with a stronger balance sheet, robust financial controls and a much keener focus on reducing our cost base.

“In addition, he was a critical part of the team which guided Marks & Spencer through the deal to create our joint venture with Ocado and subsequent equity raise.

“I look forward to continuing to work with him as we search for his successor.”

It comes just weeks after it was announced the company would drop out of the FTSE 100 for the first time since the index was created 35 years ago, after its value fell below the threshold for inclusion.

The change, which will take effect on Monday, was expected after a 45% decline in the M&S share price over the last three years.