The data used in the notebook is from UK's Office of National Statistics (ONS).
This data includes registered deaths up to 17 April, 2020. According to the ONS, there is a 5 day lag between the date of actual death and the date a death is registered, on average.
From the figure below, we can see that the overall number of deaths in London is > 3x the usual rate, as compared to the last 5 years.
Here is the same plot for all of England and Wales:
Additionally, there is a marked increase in deaths compared to the past 5 years for all UK locations and all age groups except ("Under 1" and "1-14"). This can be seen in the plots in the notebook, along with further analysis.
View the notebook for details. The plots are at the end.