Thomas Cook has announced the shock departure of its chief executive, Harriet Green.

Green has stepped down from the business with immediate affect and will be replaced by chief operating officer, Peter Fankhauser.

Green said her “work was complete”.

“The transformation of Thomas Cook into a company with a market capitalisation of just under £2 billion and a share price of over 130 pence is one I have been proud to lead.

“I always said that I would move on to another company with fresh challenges once my work was complete.

“That time is now. I wish all of the team at this re-energised company continued success, as they move to the next phase of the company’s development,” added Green.

Shares in Thomas Cook were trading at 110p per share this morning, having fallen by over 20 per cent.

Harriet Green joined the company two years ago when the company’s share price was just 14 pence and it had a market capitalisation of £148 million.

Her remit was to transform the company, placing it on a sound financial footing with a solid operational team able to compete in the consumer travel market.

Incoming Fankhauser has held a number of senior roles over the last 13 years at Thomas Cook.

He will be supported by Michael Healy, who will continue to serve as group chief financial officer, and Christoph Debus, chief air travel officer.

Fankhauser said: “I feel very honoured to be leading this business which means so much, to so many people.

“I am determined to work with all our great colleagues worldwide to build on Harriet’s achievements, continuing to deliver great holidays for consumers and good returns for investors.”