I was just thinking that with so many aircraft related sites monitored. Add Mildenhall Royal Air Force Base to the highest temps at 33c at 1.08pm.
Landuse definitely makes a difference to daytime temperatures - not UHI per se (UHI is largely a nocturnal phenomenon and is most pronounced in city centres rather than places like airports), and I the fact is airports are generally open areas, there are not so many trees around and as they are often low altitude and flat they are more likely to be in arable zones, all of which lend themselves to lower humidity, larger diurnal ranges and high daily maxes.
Essentially everywhere on the world's surface other than true wilderness areas (and nowhere in the UK) the climate is influenced by human landuse change. Deforestation in the tropics is probably the extreme example, where whole regional climates can be affected. As a species we have changed the land cover, topography, humidity, albedo, and soil moisture of vast swathes of the continental land masses. It means that, even before we consider greenhouse gases, all temperature readings in the British isles are arguably artificial, even in somewhere like Aviemore or Altnaharra.
Brockley, South East London 30m asl