It must be a very big sofa. I have never heard of having to remove sofa arms before - are you sure they need to be taken off? Whenever I've moved a sofa they never fit through a door normally - you have to stand them on end with the arms pointing one to the floor and one to the ceiling. The back goes out first and by twisting the whole thing around the door post the seat part can easily follow - I have had to remove sofa feet though, to negotiate the doorway, and they unscrew very easily.
Without actually seeing your sofa it's very difficult to offer practical advice - the fact that it's leather and from Reids Furniture is of no consequence without seeing the thing.
If you can't get it through the doorway yourself you'll just have to fall back on the people who dismantled it in the first place - I just can't imagine any sofa being made so that the arms can be removed. If your sofa has this ability you will have to look underneath the base of it for the solution. Turn it upside down and have a look.
Good luck...
Peccavi
October 2009