By Daniel Hunter
The government has been defeated in a vote over the control parent companies have over pubs.
MPs voted 284 to 259 in favour of changing the law to allow pub landlords to buy stock from the open market.
Previously "tied-pubs" were forced to buy stock from the parent company, often at very high prices.
Campaigners described it the vote as "historic" and said it would help "secure the future of the Great British pub".
It is believed to be the first bill on which the government has been defeated since the Conservatives came to power in 2010.
Lib Dem Greg Mulholland who called for the bill to be amended said: "This is a reasonable gradual process that will simply bring back market forces into a sector that frankly has become grotesquely anti-competitive."
The Federation of Small Businesses said it was "a historic day for tied publicans who look forward to a more open and competitive marketplace".
But share prices in pub companies fell after the news. Enterprise Inns' shares fell 12.6%, Punch Taverns lost 8.5% and Mitchells & Butlers shed 2.5%.