Arome was topping out at 38C and it is usually pretty accurate, plus I think temps will start to level off soon. So 38C I reckon, within touching distance but not necessarily above the record. 

Looks like Writtle and Charlwood in joint lead at midday (12z) with 35.4c

Yep, clouded over here and the temperature at a local PWS has dropped to 32C after hitting 33C earlier.

I'm only approx 15 miles from Writtle. I've got 35.0C at 13.20hrs.

WOW! That was actually quite scary.... there were a plethora of creaks and groans from the house a few minutes ago, which is unusual as it's not windy.

Something weird has happened with the weather - the dewpoint has fallen by 5C or so and the air temperature has risen by 3C in a matter of a few minutes. I suspect it was actually faster than that, the weather station taking a little while to catch up.

Any ideas, anyone? It has me stumped.

34.8C / 13.0C now.

Creaks like that are usually due to things like plastic gutters / upvc fascias / downpipes suddenly expanding due to temperature rise. Probably that. 
edit: just realised you were probably asking about the weather, rather than the noises, lol!

Cambridge University Botanic Garden weather station is surrounded by cut grass this year, which contrasts from 2019 when it was ~50% bare soil:

https://twitter.com/CUBotanicGarden/status/1548993997703708673

Check your wind direction, as here it has gone from a SE'ly to a WSW'ly over the last 20 minutes. Maybe a small heat low forming ?

This would raise your temp rapidly as air from the mainland sweeps across.

Just seen the Meto have tweeted there is a 95% chance of breaking the temp record either today or tomorrow.

36C Now in Cambridge.

Dropped back again - now 30.9C.

Wind: SSW

1pm (1200Z) update:

Cambridge 36 (rounded)
CHARLWOOD AUTOMATIC 35.4
WRITTLE AUTOMATIC WE 35.4
LONDON ST JAMESS PAR 35.1
Heathrow 35.0C
Cavendish 35.0C

In 2019:
Cambridge NIAB 35.5C
St James's Park 35.3C
Wisley 35.0C
Kew Gardens 35.7C

Cambridge airport hit 37C on the 1250Z METAR in 2019, so we are very close but perhaps a tad below.

Cloud and a bit of breeze have pegged it back to 33.2C here.

The models suggest that the south is not a contender today anyway, it will be somewhere well to the north of London, either Midlands or East Anglia. I imagine the models have factored in the breeze and cloud in this part of the world.

The extent of the heat is incredible, much more so than 2003 or 2019.

We have 32C+ currently in a big lozenge from Plymouth in the SW, all the way through Wales to the Lancashire plain in the NW, Humberside (and nearly Newcastle) in the NE and down the East all the way to Manston in the Isle of Thanet. And it's only 1.30.   

Meanwhile in France it's 38C in Brest and 40C in Nantes.

36.3c at 1:45pm

Writtle is about half mile from me it is mighty hot it is starting to have another go still sunny

https://cm2weather.co.uk/gauges

quote=Rob K;1457852]

1pm (1200Z) update:

Cambridge 36 (rounded)
CHARLWOOD AUTOMATIC 35.4
WRITTLE AUTOMATIC WE 35.4
LONDON ST JAMESS PAR 35.1
Heathrow 35.0C
Cavendish 35.0C

In 2019:
Cambridge NIAB 35.5C
St James's Park 35.3C
Wisley 35.0C
Kew Gardens 35.7C

Cambridge airport hit 37C on the 1250Z METAR in 2019, so we are very close but perhaps a tad below.

Cloud and a bit of breeze have pegged it back to 33.2C here.

The models suggest that the south is not a contender today anyway, it will be somewhere well to the north of London, either Midlands or East Anglia. I imagine the models have factored in the breeze and cloud in this part of the world.