It's last call for the early pub closing times that have shocked many a visitor to Britain since their introduction during World War I.
The British government hopes the change, which takes effect at midnight (0000 GMT) Wednesday in England and Wales, will stop the flood of drunks onto city streets just after the traditional 11 p.m. closing time.
But opponents say British consumption of booze - the most notorious, although hardly the heaviest, in Europe - should not be encouraged.
Britain's licensing laws - largely unchanged since they were tightened in 1915 to keep factory workers sober - have long been derided as an anachronism. They required most pubs to close at 11 p.m. Monday to Saturday and 10:30 p.m. on Sundays.
The new rules allow pubs, bars, shops, restaurants and clubs to apply to open any hours they like, although each license must be approved by local authorities.
Supporters say the changes will end the scramble to guzzle as much booze as possible in the last minutes before closing time and so cut down on alcohol-fueled violence.
Thousands of pubs and bars have been granted later licenses under the new rules, although the vast majority have asked for an extra hour or two - hardly the "24-hour drinking" endlessly repeated in headlines.
Only 700 establishments, including 240 pubs, applied for licenses for around-the-clock sales, according to government figures.
The government's licensing minister, James Purnell, said the new law would mean that "at last grown-ups will be treated like grown-ups."
But the new law has many opponents, including police chiefs who have warned of a rise in booze-fueled crime and health agencies who say alcohol consumption, and its attendant ills, will inevitably increase.
The government has said alcohol figures in 44 percent of violent crime, while booze-related mishaps account for 70 percent of hospital emergency-room cases at busy times, the AP reports.