St George’s Hospital has a full time Roman Catholic chaplain Fr Mark Higgins. He can be contacted directly on 020 8725 3069. If there is any kind of emergency then please call the hospital switchboard 020 8672 1255 and ask for the operator to page the catholic priest, they can even page your phone number to him and he will phone you back immediately (unless he is saying mass at the time).
When Fr Higgins is away the pager is passed on to other local Catholic priests so in emergencies there is always a priest available on the pager.
For non-emergencies you can also contact Fr. Higgins by e-mail on firstname.lastname@example.org