In reply to The New NickB:
The list you'e been given contains all the members of the DSWA operating in Lancashire.
Just a couple of points to consider when choosing someone:-
I don't think there is a great deal of conventional drystone walling skill in building/repairing these - but if I was picking someone I'd choose some one who'd done it before (OK, so I'm a bit contrary!!).
They appear rather uncommon around your area but they are relatively common in some areas of the lake district.
One practical problem you or the guy/girl you use may be finding a quarry still open which can obtain the slabs in the right thickness and size.