As you say you are not sure--but records are available. I would speculate that we get many more days in this country with a cloud base below 1000 feet than in most European countries.
In my experience of operating into Europe I have certainly made more diversions from UK airports than any other.
We also have a unique geographical make up, narrow and long, never far from high ground or the sea.
Yes Ireland gets the weather first but the number of registered pilots in Eire as opposed to the UK must be small.
Not that many countries in Europe get moist south westerleys with the Gulf Stream or first stop unstable polar maritime air.
Or the Haar!