The BTO winter atlas showed that Jays were present in most 10km squares during the winters of 1981-82, 1982-82 and 1983-84.
The darker the colour, the higher the relative total count for each 10km square. The darkest blue represents over 11 birds.
It is possible that the highest numerical plots were due to a hangover from the Jay invasion of autumn 1983.
Graham Rees