Different regions within a country will often have different timing, gradients etc
and also may have some mass public events on various dates, which will be superspreading occasions
We can understand this for Wales, Scotland and NI compared to England,
but it also applies to the English regions
London has greater international connectivity, started its cases earlier than the rest of the UK, had a higher gradient, was compliant in lockdown, had an earlier peak
The UK sums together all these different regional curves, which is another reason the UK curve has a lot of noise and blips.
We see differences between the Italian regions too
and certainly between the states in the USA, which are somewhat comparable epidemiologically to a continent with countrie