The principal boundaries are Broomwood Road, which links Wandsworth and Clapham Commons, and Cavandish Road, running from Clapham Common, to Tooting Common.
As is common these days, especially in London Parishes, it is not necessary to live within the Parish boundaries in order to worship at Holy Ghost – obviously, anyone is welcome.
Regarding the reception of the Sacraments for those living outside of the Parish, usually some arrangements can be made for those who worship weekly at Holy Ghost. Each situation needs to be discussed with one of the priests in good time.