High pressure, or to be more exact, high 500mb heights over Greenland usually has a detrimental effect on summer prospects here, but you can get poor summer weather here without those heights over Greenland, as July 1988 shows.
However, the lowering of heights over Greenland after a protracted spell can herald a pattern change which will perhaps lead to an improvement in the weather over the UK generally.
Probably why some (including myself) are very keen to see those heights drop.