Here are "poor" charts in the midst of these famous summers. The question is, will this summer go down this route, where they are just blips and the summer comes back with force or will it be like say 1868, 1921 and 2006 and have a poor August? Interestingly, even these examples had the heat coming back after the August. 

Chart for 25th July 2003

Chart for 14th July 1995

Chart for 31st July 1984

Chart for 13th July 1976

Chart for 15th July 1975

Chart for 12th July 1959

Chart for 31st July 1949

8th July 1947

Chart for 14th July 1933

Chart for 30th July 1911

Great archiving there Kevin. Amazing looking at those and just how rapidly things settled down again.

Yes, the most remarkable one in my memory is July 1976. I can remember people remarking that it could well be the end of the very long hot spell, but of course it settled down again and the rest is history!

We may face a similar situation this summer, particularly for the south. The latest Met Office forecast for the next 6-30 days:

On Saturday and Sunday the north of the UK may have cloudier and breezier conditions with some outbreaks of rain or showers, while further south there will be a good deal of dry and fine weather, with a good deal of sunshine in the south. Temperatures will be warm for many, probably very warm in the south and becoming rather humid, especially at night. Through the following week generally fine and very warm weather will predominate in the south and much of the east, perhaps becoming hot, but always with the risk of isolated showers or thunderstorms. Further north and west it may be more changeable and breezy with outbreaks of rain or showers, but with temperatures warm for much of the time.

UK Outlook for Tuesday 31 Jul 2018 to Tuesday 14 Aug 2018:

Throughout this period it seems most likely that there will be a continuing northwest / southeast split in the weather. Southeastern parts are most likely to see periods of dry and warm weather, with brief interludes of more showery conditions. Some very warm or hot spells could develop in the south at times, but these would bring an increased risk of thunderstorms. Meanwhile further northwest, any settled weather will probably be shorter lived, with rain or showers at times, but also some drier and sunnier spells. Temperatures are expected to continue above average, with some warm or very warm spells possible outside of any persistent showers or rain.

Updated at: 1347 on Mon 16 Jul 2018

If this forecast were to materialise, then summer 2018 could very well challenge for a Top Five position in the CET summer series.

I assume you trawled through 1983 but found nothing you considered worthy of inclusion?

Well there is this on August 1st. http://i1075.photobucket.com/albums/w430/Reddwarfer123/NOAA_1_1983080100_1_zpso3jqz4eg.png

Looks pretty unpleasant, especially for the SE corner.

Would have prefered to directly paste the image in, but couldn't get it to work.

Great work Kevin .

Most of these charts feature simultaneous ridges to the south and east/northeast. 

These working together seems to be our most reliable 'saviour' whenever an Atlantic trough finds its way in during the summer months. The ridge to the south is most important of course; it prevents the low from becoming stuck to the south of a ridge from our E/NE. Just having a Scandinavian high isn't usually good enough, though we did quite well at times in July 2014 for example.