But how big is the new "mega embassy", as it is often called in the UK media?

China purchased a 20,000-square-metre (235,000-square-foot) plot of land, known as Royal Mint Court, next to the Tower of London, in 2018.

Compared to other embassies around the world, the plot size is comfortably outside the top ten, which is dominated by US embassies in the Middle East -- the largest being its 420,800-square-metre compound in Baghdad, according to the US government.

China's embassy in Islamabad, measuring around 1,580,000 square metres according to satellite imagery, is also substantially larger than its planned London project.

But it is an unusually large plot for an embassy in the historic heart of a capital city, particularly in Western Europe.

Governments do not publish the official size of all their embassies, but the US embassy in Rome, measuring 26,000 square metres according to satellite imagery and information published by architects who worked on the compound, appears to be the largest plot.

Given scarce data on actual office space within embassy compounds around the world, plot size is often used as a benchmark as it can be assessed by satellite image.

Most sprawling compounds on the edge of Middle Eastern and Asian cities are low-rise, making it a useful metric, but embassies in city centres are often multi-storied, including the disputed Chinese embassy in London, meaning their true size may be underestimated.

The UK also publishes planning documents which show that the Chinese embassy's projected floor space exceeds 50,000 square metres.

This would make it London's largest embassy, ahead of the new 12-storey US home around 5.1 kilometres (3.2 miles) to the southwest and with a floor space of 48,000 square metres, according to its website.

It would also make it the largest Chinese embassy in Western Europe, and likely the largest embassy of any country in the region, by floor space.