To be clear they are talking about the air temperature rather than runway temperature and I've added the latitude so you can understand why it's a big deal that London has hit 40 degrees.
That’s weird, some cursory searches show a definite upward trend for quite some time, i do find these weird sites where they consistently pick outliers in a dishonest manner. It really wouldn’t be worth engaging with them though
Latitude of London, UK: 51.5° N
To be clear they are talking about the air temperature rather than runway temperature and I've added the latitude so you can understand why it's a big deal that London has hit 40 degrees.