London will move to tougher Tier 2 coronavirus restrictions from Saturday 17 October.
People from different households will be banned from mixing indoors - including in homes, restaurants and pubs.
It will mean around nine million will see their social lives considerably restricted.
But coronavirus rates vary from borough to borough, with some council leaders calling for localised action instead of a blanket rule.
Richmond had the highest weekly infection rate in London - with 110.7 cases per 100,000 people - for the week 5 to 11 October.
Hackney and City of London was next with 108.5 cases per 100,000, and Ealing third with 107.6.
At the other extreme, Bexley had the lowest weekly infection rate - 48.9, followed by neighbouring Bromley at 49.8.
These numbers are far lower than some parts of the north and the Midlands where Tier 2 restrictions are already in place.
Nottingham, for example, has a rate of 766 per 100,000, after 2,536 new infections were recorded in the past week.
Newcastle's weekly average was 448.4, following 1,346 cases between 5 and 11 October.
The figures indicate the virus is spreading faster in parts of the country where the risk level is now considered the same as London's.
In the Liverpool region - the only area in England currently under "very high" risk Tier 3 restrictions - the rate is 603.7 cases per 100,000.
In Derry/Londonderry in Northern Ireland, which this week announced a four-week "circuit-breaker" lockdown, the weekly average is even higher - 978.2.
That's many times higher than the worst-affected London borough.
However, comparisons between recent case rates should be made with caution.
The number of confirmed cases is heavily dependent on the number of people being tested, which varies from region to region.
Sadiq Khan insists current case numbers in London are inaccurate because testing capacity has been insufficient in recent weeks.
He believes there are more people in the city with the virus than is officially being recorded.