Hi Barry
Thanks for your replies!
Typically now the kids have gone back to school the weather has been too wet to go out and do anything to the car!
Anyhow, I have measured the wheels and both are the same offset - measured from the backs of the wheels to the mating faces (to the drums).
I have used a spirit level (straight edge) to make several other measurements from the drum faces to the shock absorbers, drum faces to the beam, back of drums to the beam and several others to the bodywork but all measurements are the same each side.
I have checked the spacers and both sides are 20mm.
The beam bushes are poly and the beam sits central to/on both bushes.
The front faces of the wheels are, according to the spirit level/straight edge, in line with the top areas of the arches.
I have made a couple of observations...
* The passenger side rear wheel when viewed from above 'looks' like its turned out slightly on the edge facing forward. I could describe it looking like its toed out too far towards the curb, but when viewed from the front along the face of the front wheel it looks straight.
* The rear bumper on the passenger side is not attached as the securing 'clip' is broken. To get the bumper to sit where it should I have to push it in towards the car. I would have thought that if it is protruding away from the car in what appears to be its natural/unsprung position, then possibly there has been some panel damage on the rear side which makes the tyre on that same side appear to be out further than the other side.
I never noticed this issue when I had the standard wheels fitted so maybe the slightly wider wheels has made this more obvious as they are further out towards the arches.
I can put two original wheels on the back and check some measurements and also have a spare rear beam I can fit but that would be a last resort knowing that the bushes would need replacing first!