Summer1980 was indeed a bad summer. I was at a weather observer's course at Shinfield College near Reading in June then back to working at Herstmonceux, East Sussex in July and August.
June was cool, wet and thundery with places having up to 10 days of thunder. Sunshine figures were not too bad for that month because June got off to a good start.
Early and mid July was absolutely atrocious for coolness, dullness and wetness. The day maximum was 13.3 deg C at Herstmonceux on 1st. However, from 21st, it became much warmer, drier and sunnier to restore some respectability to July's figures. The absolute maximum of the summer was 26.3 deg C on 25th July.
August was also poor. The 14th was an extremely wet day because of evening and overnight thunderstorms that day.
Certainly a cool, dull and wet summer.