Sky News has learnt that Ovo, the UK's biggest independent energy supplier, will announce on Thursday that it has recruited Adrian Letts to become the chief executive of its retail business.
The appointment will underline the intent of Stephen Fitzpatrick, Ovo's founder and CEO, to continue growing its retail market share, just 24 hours after the competition watchdog gave the green light to the merger of SSE's retail arm and npower, the German-owned supplier.
The recruitment of Mr Letts is a coup for Mr Fitzpatrick, according to market sources.
The Tesco executive, who informed colleagues on Wednesday that he was leaving Britain's biggest grocer, was a co-founder of Blinkbox, the digital and on-demand television service bought by the supermarket chain during the ill-fated reign of Philip Clarke, the former chief executive.
Ovo now has more than 850,000 retail customers, a base it has built from a standing start in 2009, although its efforts to become sustainably profitable remain a work in progress.
Last year, it reported a pre-tax profit of £6m, down from £24m the previous year, according to accounts filed at Companies House.
In 2015, Mr Fitzpatrick sold a stake to Mayfair Equity Partners, a London-based investment firm.
He told Sky News that Mr Letts was "one of Europe's stand-out talents in the digital economy and is joining Ovo at a time of profound change in the energy sector across the world".
"His experience running a global digital business at a leading retailer, combined with his entrepreneurial mindset will be key in helping shape our strategy, and lead our international expansion to Europe and beyond," he added.
Mr Letts will partly replace Chris Houghton, Ovo's chief financial officer, managing director and retail CEO, who is leaving to focus on entrepreneurial opportunities in the cycling sector, according to the company.
Ovo recently bought a majority stake in 4hundred, a German energy provider, an important stage in its international diversification.
Its UK-focused acquisitions have included Corgi HomePlan, which operates through a network of thousands of engineers and provides home maintenance insurance plans to more than 150,000 UK customers.
Mr Fitzpatrick has been a trenchant critic of the current crop of big six suppliers, which include British Gas and Scottish Power, for failing to provide their customers with reasonably valued tariffs or acceptable levels of service.
Ovo enables customers to pay an additional charge each month to guarantee that their electricity is supplied from renewable sources.
A looming price cap drawn up by Ofgem on the orders of Theresa May has drawn a mixed reaction from the crop of challenger brands which have sprung up in the market, some of which have since thrown in the financial towel.
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Nevertheless, the Competition and Markets Authority said on Wednesday that it saw no reason to block the SSE-npower tie-up, saying it would have little impact on prices and controversial standard variable tariffs (SVTs).
It found the two companies were not "close" rivals when it came to the thorny issue of default tariffs - with SVTs also set to face a government-inspired price cap from this winter.