The summer of 1975 had two prolonged heatwaves in Central England, and averaged three degrees warmer than this year’s “record hot summer.”
12 Aug 1975, 6 – The Guardian at Newspapers.com
Similarly, the following summer was five degrees warmer than this year.
The 1975 heatwave wasn’t enough to erase post 1940’s global cooling however. That required data tampering by NASA and NOAA.