I'm guessing some media article sensationalised that and claimed it was abnormal and due to climate change? There are issues with some of the data, as they have been 'adjusted' due to instrument changes or site moves, and the tendency should be for many to measure warmer temperatures as buildings get nearer, but even allowing for all that, 9 degrees is pretty much normal. Select some other years for comparison, and you could argue it's a sign of cooling. https://www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/heathrowdata.txt
If you plot the maximums from the met office's own data, they can be quite interesting in a nerdy sort of way. https://www.metoffice.gov.uk/research/climate/maps-and-data/historic-station-data
Just remember that the Lefty Loony Grauniad reading cotton slave trade supporter tries to engage in conversations with statues on benches. He's not the brightest.
Blacks hate them too . https://www.jewishnews.co.uk/teenager-charged-over-stamford-hill-attack-on-two-orthodox-men/
But, but Lefty do-gooder Wokes keep telling the world that it's only whites that are racist They really don't have a clue. Racism occurs within all colour types, it's just that Lefty Loonies want you to believe that only privileged white people (like Dame Stormer for example) are racist.