Hi Jo, the name Heffernan comes from Ireland, Limerick.
Usually when you have a surname as a second name. The parents usually name this way when a person in the family
has some kind of wealth, or the name has past down because
it was someone important in the family.

Have you looked at the census for your family in England,
then you may get and idea if there were any Heffernan's in
your line or if they married into one.

The Heffernan name is vast.

Paulette