Fuller's, the brewer whose beers include London Pride, is to sell its entire drinks business to Japan's biggest brewer Asahi.
The company said the £250m deal would preserve the Griffin Brewery in Chiswick, west London, where beer has been brewed since 1654.
Fuller's will now focus on its hotels and pubs business, which generates most of its profits.
Asahi is the owner of the Peroni and Grolsch brands.
Fuller's said the deal - which also includes cider and soft drinks brand Cornish Orchards and craft cask brewer Dark Star - was due to "structural changes to the beer industry".
As a mid-sized brewer, the company said it was being squeezed between the global brewers and the 2,000 smaller brewers across the UK.
The Campaign for Real Ale (Camra) said it was a "sad day" for the industry.
Fuller's is forming an alliance with Asahi to enable its pubs and hotels to continue to sell the beers and ciders.
Simon Emeny, chief executive of Fuller's, said: "The deal secures the future of both part of our business including protecting the heritage of the Griffin Brewery in Chiswick, which was particularly important to the Fuller's board".
While the Griffin Brewery dates back to the era of Oliver Cromwell, the business - full name Fuller, Smith & Turner - was formally created in 1845.
Mr Emeny is the first chief executive of the business not to have come from one of the founding families, taking over in 2013. Just over 50% of the shares are still owned by descendents of the founding families.
Neil Wilson, chief markets analyst at Markets.com, said: "Punters won't notice much difference at the bar. Pubs may be closing at a hell of a clip these days but consumers still want experiences and dining out is one of those.
"Therefore investing in pubs and hotels is essential as consumers demand more from their pub experience."
He said the deal was well timed because of the fall in the pound.
"Right now with the pound still very undervalued it looks to be a good time to swoop. The Japanese firm has been gobbling up brewers across Europe and elsewhere on major buying spree."
Analysis: Little space at the bar
By Katie Prescott, BBC Radio 4 Today business presenter
Like the ravens leaving the Tower of London is how one commentator described the sale of London Pride to Asahi.
But while there may be an emotional significance, drinkers are unlikely to notice a change to the branding or formula in the pub. The two companies have signed a long-term strategic alliance and Asahi has committed to supporting the UK breweries behind Fuller's brands.
Fuller's plans to focus its attention on its pubs and hotels where it makes 87% of its profits.
It says that tax breaks given to microbrewers and the power of the big global drinks firms has left little space at the bar for those in the middle.
It's giving some of the proceeds to shareholders and its pension fund, and with a 22% rise in its share price this morning investors are certainly clinking glasses at the deal.
Asahi has already expanded in Europe by buying the Peroni, Grolsch, Meantime and Pilsner Urquell brands.
Akiyoshi Koji, chief executive of Asahi, said the Fuller's brands would complement its existing brands in the UK. "In particular, London Pride is a fantastic brand with a illustrious heritage dating back to the 1950s".
Asahi will continue to brew at the Griffin Brewery and is already a supplier to Fuller's hotels and 400 or so managed and tenanted pubs in London and the South East.
Jackie Parker, chair of Camra, said she was concerned that consolidation was "seldom beneficial for consumers".
"Fuller's has been a family brewer in Britain for more than a hundred years, and it's a very sad day to see such a well-known, historic and respected name exit the brewing business.
"While the Fuller's family has stressed it has sought to protect the heritage of the Griffin Brewery, we'd call on the new owners to pledge to continue brewing operations at the Chiswick site."
Fuller's also issued a trading update, which Mr Emeny described as "very good", adding he was "particularly pleased" with sales at its managed pubs and hotels over the key Christmas and New Year period.
Like-for-like sales - which strip out new openings - at its managed pubs and hotels rose by 4.7% over the 42 weeks to 19 January, whereas beer and cider volumes were flat.