Simplify the following text for a Grade 9 native English-speaking person.
Original: Wirral is a metropolitan borough in Merseyside , North West England , which occupies the northern part of the Wirral Peninsula , more commonly known as Wirral .
Simplified: The Metropolitan Borough of Wirral is a metropolitan borough of Merseyside , in North West England . It has a population of 311,200 , and encompasses 60 s of the northern part of the Wirral Peninsula .