Mid-April 1966 was exceptionally dull in the south. I was 12 years old living in Essex and I remember a period of snow for a time which lay during one afternoon (I should think 14th or 15th) because there was no April sun to thaw it. At Cardington sunshine was recorded on only one day during the period 11th to 20th April and it including a long period of snow on 14th and 15th - a thoroughly miserable spell of weather being cold and wet as well.
Early August 1968 was exceptionally dull in the South East at least because of low pressure over the near continent.
I was working at Dunkeswell for a few years during the 1990's. I remember November 1994 was persistently dull with 26.8 hours of sunshine, but as already mentioned, January 1996 was also exceptionally dull with 19.8 hours, though not nearly as other places in the country.