Boris Johnson has introduced a three-tier system to combat rising infections, allowing restrictions to be brought in locally rather than nationwide.
Millions of Londoners will be banned from meeting indoors as the UK capital enters coronavirus high alert.
The city will join Essex, York and others moving into Tier 2 restrictions.
Liverpool is so far the only major city to face the toughest Tier 3 restrictions.
How does England’s three-tier lockdown system work?
Every area of England now falls into three categories of alert - Tier 1 (medium), Tier 2 (high) and Tier 3 (very high) - depending on the local infection rate.
What are the rules for Tier 1?
Areas classified as Tier 1 or medium alert fall under the standard coronavirus rules.
The rules include the rule of six, which prevent more than six people meeting indoors and outdoors, and the 10pm hospitality curfew.
What are the rules for Tier 2?
Those in areas under Tier 2 or high alert are not allowed to meet indoors with people they do not live with - including in their homes, pubs and restaurants.
People in single-adult households are still allowed to meet with people in their support bubble.
There are also exceptions for in-home care and childcare.
People can still meet friends and family outdoors, but only in a group of up to six people, while the use of public transport is discouraged.
The rules for Tier 1 also apply in Tier 2.
What are the rules for Tier 3?
Areas with the highest rates of transmission are placed in the Tier 3 or very high alert level.
People are not allowed to meet socially with anybody who is not part of their household.
Residents are not allowed to meet their support bubble indoors or in certain outdoor locations.
Pubs and bars must close unless they are serving meals - and alcohol can only be served as part of a meal.
People are also advised not to travel in or out of Tier 3 areas other than for work, education or care responsibilities.
What about Scotland, Wales and Northern Ireland?
England’s three-tier system does not apply in Scotland, Wales or Northern Ireland.
However, local restrictions apply.
In Scotland, more than three million people are subject to tougher restrictions until October 25.
All licenced premises in Glasgow and Edinburgh have to close indoors and outdoors.
Elsewhere in the country, pubs can only serve alcohol outdoors as long as the drink comes with a meal.
In Northern Ireland, schools will shut for two weeks in an extended half-term break from October 19.
Pubs, bars and restaurants will also close.
In Wales, people from parts of the UK which have high rates of infection will be prevented from travelling to Wales.
Pubs, cafes and restaurants have to stop serving alcohol at 10pm.