The Co-operative Group today confirmed its intention to close Somerfield's headquarters in a move affecting around 750 staff.
The UK's biggest mutual retailer said it expected the Somerfield HQ in Bristol to shut around 18 months after the completion of its takeover.
The Co-op hopes to be able to relocate "as many as possible" of Somerfield's Bristol employees to the merged head office in Manchester.
The news came as it set out its initial integration plans for the supermarket group, which it is acquiring for £1.6bn - a deal that will cement its position as the UK's fifth biggest food retailer. The takeover is expected to go through in the next month.
Co-op will run the Somerfield business separately for up to two years as it converts acquired stores to its new shortened brand, The Co-operative.
A £70m advertising campaign begins tonight to officially launch the new brand, which adds to a mammoth £1.5bn store revamp programme as the group seeks to promote its mutual and ethical credentials.
Somerfield has historic ties in Bristol dating back more than 130 years, having first started life as a small family grocery store in the city.
The business was set up by JH Mills in 1875, later expanding into a chain and then rebranded as Gateway - Bristol being known as the "Gateway to the West" - before being converted to Somerfield in 1994.
A spokesman for the Co-operative Group said it was too early to comment on potential job losses ahead of the Bristol closure.
He added: "Somerfield has some great people and during the integration process we will endeavour to offer relocation opportunities to as many of them as possible."
The Co-op is taking on more than 650 Somerfield stores, but has had to offload 133 branches in areas where watchdogs had concerns over competition.
The enlarged group will have around 2,800 outlets and is set to make it a stronger rival to the UK's big four supermarkets.
Manchester-based Co-op, which has 3.1 million active members, is looking to capitalise on a revival in its fortunes, with the rebrand exercise part of a plan unveiled last April to double profits within three years.
The group - which also has interests in sectors including funerals, travel, pharmacy and financial services - has seen 12 successive quarters of like-for-like food sales growth.
Peter Marks, chief executive, said: "We are currently witnessing a renaissance of The Co-operative.
"More than one million members have joined us since we reintroduced our famous dividend in 2006."
Its ad campaign will air for the first time on television tonight in the middle of Coronation Street, using Bob Dylan's famous song Blowin' In The Wind.
It will also be shown in cinemas, along with a series of ads in the national press.
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