Brian,
Most traditional full sets have the bass regulator reedcap extended across the drone stock and where it rests on your forearm in a cradled position. I think Gallagher does this fitting slightly different, where the extension isn't needed and the drones and regulators sit more level.
http://www.uilleann.com/images/stainless.jpg
I didn't see the extension in the picture. I'm sure after you get your pipes you'll decide if a strap is needed or not.
Boyd started this topic... and I agree with Christian that we all differ in physical size and not all pipes/bag configurations are the same... therefore not everyone finds this a problem. I know my drones like to slide toward my knee and I'm contemplating attaching the popping strap & drone support to the bellows waist belt... one day perhaps.
I'm thinking an adjustable nylon guitar strap could be fitted instead of a strip of leather. The nylon would probably be more comfortable.