Allera’s departure follows that of Three CEO Kevin Russell who announced he was leaving last week to return to Australia. Russell will be replaced by Dave Dyson.
The sales and marketing director role will be split between current sales director Amanda Lambert and Three Austria marketing director Tom Malleschitz.
Allera says he aims to lead at the “highest level” and is also actively considering international opportunities, although he adds that he is open to taking up another position at Three parent company Hutchson.
During his tenure at Three, Allera led a rebrand of the company and its move away from promoting cheap tariffs to a focus on mobile internet.
Elsewhere in the mobile industry, Three rival Orange announced yesterday it is to invest £400m in updating its mobile networks across Europe in anticipation of increased demand for internet services.