Original: Taking its name from the River Mersey , the title '' Merseyside '' came into existence as a metropolitan county in 1974 , after the passage of the Local Government Act 1972 , and the county consists of five metropolitan boroughs adjoining the Mersey Estuary , including the City of Liverpool .
Simplified: Taking its name from the River Mersey , the title '' Merseyside '' came into existence as a metropolitan county in 1974 .