From the Wikipedia page on the park 
Finsbury Park is a public park in the London neighbourhood of Harringay It is in the area formerly covered by the historic parish of Hornsey, succeeded by the Municipal Borough of Hornsey. It was one of the first of the great London parks laid out in the Victorian era. The park borders the residential neighbourhoods of Harringay, Finsbury Park, Stroud Green, and Manor House.
From the Wikipedia page on the area 
Finsbury Park is an area in north London, England which grew up around an important railway interchange at the junction of the London Boroughs Islington, Haringey and Hackney.. It is not to be confused with Finsbury, which is 3.3 miles (5.3 km) farther south in the London Borough of Islington, although in some local contexts the name is shortened in this way.