[summer '85]

July 1988 was very poor with a succession of Atlantic low pressures steam rolling in, there were very few dry days and there was not one day where an anticyclone sat over the country. It was also cool with many places having their highest maxima being less than 20C and not one place recorded a maxima of >25C, the highest anywhere was at Margate on the 21st and 23rd with 24.7C. The overall CET for the month was 14.7C. The inclement weather badly affected outdoor events, the men's singles final at Wimbledon was practically washed out and had to be carried onto the Monday, the Royal Agricultural Show at Stoneleigh had to be suspended because of a waterlogged ring and the Saturday round of the Open Golf Championship at Royal St Lythams had to be abandoned because of flooded greens and bunkers. The 25th was a particularly bad day across northern parts with gales bringing down trees and blocking roads. A 78 mph gust was recorded at Invergordon and Leuchars and a 77mph gust at Leuchars. Here's some data from that month

Heathrow
Mean Max: 20.0C (-2.0) Highest Max: 23.0C Sunshine: 162hrs (85%)
Rainfall: 76mm (149%) Number of dry days: 8
Cardiff
Mean Max: 17.6C (-1.9) Highest Max: 19.7C Sunshine: 164hrs (81%)
Rainfall: 144mm (200%) Number of dry days: 6
Plymouth
Mean Max: 16.5C (-2.6) Highest Max: 18.3C Sunshine: 181hrs (85%)
Rainfall: 98mm (151%) Number of dry days: 14
Elmdon
Mean Max: 18.4C (-2.0) Highest Max: 21.6C Sunshine: 147hrs (82%)
Rainfall: 104mm (200%) Number of dry days: 6
Manchester
Mean Max: 17.8C (-1.6) Highest Max: 21.5C Sunshine: 124hrs (78%)
Rainfall: 134mm (172%) Number of dry days: 8
Glasgow
Mean Max: 17.2C (-1.5) Highest Max: 20.5C Sunshine: 125hrs (76%)
Rainfall: 147mm (216%) Number of dry days: 9
Aberdeen
Mean Max: 17.2C (-0.4) Highest Max: 22.6C Sunshine: 167hrs (107%)
Rainfall: 84mm (111%) Number of dry days: 6
Belfast
Mean Max: 17.1C (-1.1) Highest Max: 19.3C Sunshine: 123hrs (87%)
Rainfall: 120mm (169%) Number of dry days: 4

[Steve M]

Manchester
Mean Max: 17.8C (-1.6) Highest Max: 21.5C Sunshine: 124hrs (78%)
Rainfall: 134mm (172%) Number of dry days: 8

.. This is quite an amazing stat because for the first 4 days so far this July temps have been well above 21.5C each day.
July 1988 sounds like a horrible month going of those stats though. I do vagually remember it actually, just the precific year I'm not sure of, but I remember one July during the late 80's was a complete washout and I was fed up stuck in doors during the summer holidays (I would have been just 9 years old in 1988).