AO World founder John Roberts returns as CEO

Roberts led the business until February 2017, when Caunce became CEO, allowing him to focus on innovation and development projects.

"He now has a renewed energy to focus on the business he created and to lead AO on the continued execution of its strategy," the company said.

Roberts said: "Steve has played a vital part in AO's development and in the last two years has created the foundations for our future success. I look forward to continuing to work with him, as I have over the last 13 years.

"AO's future is incredibly bright given our depth of talent at all levels of the business. I am fully committed to the business and the execution of our focussed strategy and can't wait to get stuck in again as CEO as we move onto the next exciting stage of the AO story."

Shore Capital analyst Greg Lawless said the return of Roberts as CEO was "a surprise".

"AO is at a critical phase in its development, in our view. The UK electrical market remains as competitive as ever particularly given current consumer sentiment and a more aggressive competitor in the form of Dixons Carphone, under new leadership, alongside Amazon, Argos and John Lewis. Additionally, AO just bought an online mobile phone business in the UK, so the overlap between the business and Dixons is even more pronounced.

"In Continental Europe, the company remains sub-scale, seeking to move towards an EBITDA breakeven in FY2021. Whilst the vision is commendable, the financial stress remains considerable too. We wish Steve well in his new part-time role and look forward to hearing from John Roberts, as CEO, in time. We continue to respect the culture and infrastructure that the company has built, but on valuation metrics reiterate our sell rating."

At 1125 GMT, the shares were down 2.4% to 121.80p.