But if the Shropshire cloud effect was persistent, then it would be reflected in the averages and not the anomalies. All of your examples with relatively less sunshine in Shropshire compared to elsewhere in the country would therefore be cancelled out by examples of Shropshire getting relatively more sunshine in the rest of the country.http://www.metoffice.gov.uk/climate/uk/averages/ukmapavge.html You can get averages here. Perhaps it's because Shropshire finds itself between the Irish sea coast, which has plenty of sunshine, and the south, which also has relatively more sunshine but doesn't benefit from either of these locations. But it's still sunnier than the upland areas surrounding Shropshire.