OK so having spent New Year in the Lake District I was determined to get to the bottom of this suspension issue - unfortunately I failed at the 2nd hurdle.
Got back home last night so out in the rain this morning to take both the fronts off - got the drivers side off but knackered the locking wheel bolt (I hate them) socket trying to remove the passenger side. The annoying thing was I'd already had the passenger side off but clearly didn't exercise enough caution when fitting the bolt.
However, taking the drivers side off did reveal a spacer was fitted so now I'm thinking it must not have been replaced on the passenger side by whoever replaced the wheel prior to me getting the car. My only doubt with that assumption is that visually the wheels look the same and the bolt lengths are also the same.
The spacer that was on looks pretty crap and doesn't have any markings other than the # 2 stamped on it - seems to be 7mm.
Anyway I now need to wait to check the passenger side, which is where I have the issue, until I can get a replacement locking wheel bolt socket