The Wirral Line is an underground railway service operating in which UK county?

Delan1947, No more obscure than some other questions. Anyone living in or around Merseyside would know the answer, as would plenty of the millions of tourists who have been to Liverpool.

Player #37065801, There is, actually.

There is NO such county as Merseyside!!!

Delan1947, surely that's the whole point of trivia