Thanks, I have checked (actually replaced) the breather pipes and also checked timing and mechanical/vacuum advance - so they are all OK. There is no misfire, the exhaust note is pretty stable as is the idle it is just "lumpy" i.e. the engine moves about quite a bit (yes the mounts are a bit soft - on the todo list - and I don't think the front stabiliser bar thingy helps as it tends to make the engine skew rather than rock which accentuates the problem)
Steve, I think that answers the question - "idle on a Sprint is never silky smooth" - and is kind of what I assumed. My son has a 106 Rallye with the 8 valve 1.3 engine and the idle on that is similar - i.e not smooth, so as you say could be related to the more aggressive cam timing.
I don't think it should moving around excessively, once I had mine setup properly it wasn't doing that. Saying that i have replaced all but one of the engine mounts, including using the alternative gearbox mount recommended here, plus a new steady bar. So that could be the reason for the difference.