The Co-operative Group joined forces with a smaller rival this weekend to form the biggest mutual retailer in the world.

The Manchester-based chain has merged with mutual grocer United Co-operatives, based in Rochdale, with which it already shared purchasing arrangements.

The enlarged Co-op now has a turnover of £11 billion and some 4,500 outlets, including 2,300 food stores.

Martin Beaumont has retired as chief executive, allowing Peter Marks, the chief executive of United, to run the enlarged business.

His aim is to get the Co-op’s widespread operations - it also runs funeral care services, shoe shops, pharmacies, travel agencies and is also the UK’s largest farmer - pointing in the same direction, with the goal of creating “one business in one year”.

More emphasis will also be put on building the Co-op brand.

Marks said: “We are fortunate that both societies are committed to broadly the same business strategy in each of the markets they operate in, so we are not talking about major upheaval and change.

“We will be building on the work already under way by improving and extending our store portfolio, continually improving our customer offer and, for the first time, driving real competitive advantage from the great work that has been done to unite the co-operative brand and engage with our customer members.”

The emphasis is on being a “community” retailer with a strong neighbourhood presence, rather than in trying to match bigger retailers across all formats. “We are the largest community retailer in the UK with an unparalleled position at the heart of thousands of communities,” Marks said. “A rejuvenated co-operative brand and membership offer underpinned by better shops, better products and better service will give us powerful market positions in each of the sectors we operate in.”