OBone wrote:
I need to run several cables from my internal garage into my loft, but I
don't wish to run them up the outside of the house. The problem is running
them through a first floor dividing wall that is made from two pieces of
plasterboard that has an egg box type construction between them. How does
an electrician get over this problem when wiring in wall switches?

Take a 40mm or so spade bit.
Drill hole in wall.
Drill hole in eggbox stuff at as steep an angle as you can, using a
long-reach bit.
Repeat till you've got a clear channel all the way up.
Avoid existing cables.