Drinkers visiting pubs in tier two regions will have to leave when they finish eating, under new restrictions being introduced from 2 December, No 10 has confirmed.
Under the post-lockdown guidance, pubs in those high risk areas can only open if they function as a restaurant.
And alcohol can only be served as part of a "substantial meal".
Pubs and restaurants are currently closed across England, apart from for takeaways.
The prime minister's official spokesman, asked how long drinkers can stay in a pub after buying a meal, said: "We've been clear that, in tier two I believe, that you need to have a substantial meal if ordering any alcohol and it remains the case that the guidance says that once the meal is finished, it is at that point [you have to leave]."
When the current lockdown ends, the rules will change according to where you live.
In tier two regions, pubs and restaurants must shut at 23:00 GMT, with last orders an hour earlier.
You can only socialise inside with people you live with, or those in your support bubble if you live alone. Groups of up to six can meet outside, but social distancing must be adhered to.
In tier three, very high risk areas, you cannot mix with anyone outside your household either indoors or in pub gardens or private gardens. Hospitality venues - such as bars, pubs, cafes and restaurants - must stay closed, except for delivery and takeaway services.
In tier one, medium level, people can meet inside or outside in groups of up to six. Most of England is in tier two or three, however, with only Cornwall, the Isle of Wight and Isles of Scilly in tier one.
Stricter measures for pubs, restaurants and bars will come into force in Wales on 4 December, it was announced on Friday.
Northern Ireland is currently in a two-week circuit-breaker lockdown, with cafes, coffee shops, pubs, bars and restaurants closed, except for takeaways and deliveries. And in Scotland, the rules on pubs and restaurants depend where your region is placed in the four-tier system.