Interesting - you're both right, it's not on the official list:

https://www.metoffice.gov.uk/research/climate/maps-and-data/uk-synoptic-and-climate-stations 

I'm surprised it's still appearing on the likes of NetWeather's lists in that case!

PS - Ian, you're dead jammy to have protection from the winds today. There have been some ferocious gusts here, into the 50s, and I've lost some of the decorative coving from my porch. Thankfully despite the roar nothing else has gone wonky yet...

Might not be MetO official but it is Metar official.

https://en.allmetsat.com/metar-taf/united-kingdom-ireland.php?icao=EGUN 

add: we were at 17°C for much of last night into this morning. 

https://www.weatherobs.com/ 

Remarkable if confirmed seeing that there's no augmentation from a Fohn effect. I would have thought that RAF stations would be reliable in respect of measurements

Checking my database of Kew Gardens daily temps from 1893 I believe this is the 6th greatest 3 day increase in the last 131 years

The only days to beat this are shown below and only 1 of these is in the Autumn/\winter period being for December 1916

Lakenheath 13:55 reading was 19.2ºC. Remains to be seen whether that will be counted as official.

https://www.extremeweatherwatch.com/cities/buxton/year-1975 

June 2nd 1975 was the day that the County match in Buxton got snowed off. 

https://www.itv.com/news/central/2015-06-02/waiting-for-summer-to-start-it-was-much-worse-in-1975 

Met office have Santon Downham at 18.7c as the max today. 3 days ago it's max was 2.7c.

Not necessarily - they've just said that at Santon Downham it was 18.7, rather than it being the warmest place in the UK.

I wouldn't be at all surprised to see a 19 appear on the official stats later - I won't know until tomorrow, but night owls will see it appear here around 11PM:

https://www.metoffice.gov.uk/weather/observations/weather-extremes 

True theys don't actually say it's today's max. So maybe somewhere has crept over 19c.

"Some of the county's gritter lorries are named after famous Lincolnshire residents, including the Spread Arrows, Sir Ice-ac Newton and Mar-grit Thatcher."

Gritters cover almost 30,000 miles during cold snap

https://www.bbc.co.uk/news/articles/c3vl04yg23ro 

Official stats give Santon Downham 18.7 C as yesterday's highest max

https://www.metoffice.gov.uk/weather/observations/weather-extremes 

But, as you say, there could be an unofficial but still reliable value a point or two higher nearby

Yesterday's official highest rainfall was 72mm at Libanus, just north of the Brecon Beacons, but given the severity of the floods in the Valleys, I wouldn't be surprised if somewhere there posts a higher total.

EDIT - extending it beyond 24 hours Since 21:00 GMT on Friday, 150-190mm of rain fell widely in Dartmoor and Brecon Beacons  from Matt Taylor  https://www.bbc.co.uk/news/live/ckg7w7xzrj3t 

At least that confirms that the MetO ignore the US air bases! Odd, as you'd have thought that the military would have had decent equipment / procedures for monitoring.

At long last the wind's died down here, following an unpleasant 36 hour blast... I see there's been some minor rearranging of things in the garden, so the squall around midnight must have been quite strong! I'd relocated my bed to the opposite side of the house, so had a quieter night without guttering and soffit boards creaking.

It's now mostly cloudy, following 3.8mm of rain overnight, and temperatures are on the way down - it was 16C at midnight!

It's currently 10.2, dew 9.1, with yesterday's high being 17.2.

Apart from that, today has started off on a bright note with some decent sunny spells though with the odd blustery shower earlier on.

Currently around 7°C here in Edinburgh.

A more seasonal 11.5 C, it peaked at 16.2 C at 11.20 am yesterday. 8.8 mm of rain since my 12 am station reset. 

Windy with blustery showers off the Irish sea. 

Chilly at 6.2c

Bert didn't wet us too much but he certainly caused The Central Belt some trouble with more snow than expected. His sting in the tail has given us a stormy 18hrs too! 52 mph today.

My thoughts once more are with the flood victims further south, particularly in south Wales 😱

Edit. Mist and frost after drop in temp.