It depends on which Philip you are looking for.
What was his age in 1871?

Further to Frances's note.
In all censuses to 1901 there were 21 basic enumeration districts - the 17 parishes plus the towns of Castletown, Douglas, Peel and Ramsey.

There were also separate enumerations of Public Institutions such as the Barracks, Gaol, Lunatic Asylum, House of Industry. Later the Hospital, and KWC.

In my published indices the birth place as given in the census is shown by a three letter code.