Another nice sunny albeit cold day so thought I would finish off the jobs this arvo.
Opened up the existing clip holes to approx 4 mm and cleaned up both faces with a file,attached to manifold with bolts/nuts and threadlock,fitted new oil separator pipe.
I had ordered a set of 10 x small bottle/pipe cleaning brushes which fortunately arrived this morning and used one of the smaller ones to finish off cleaning out the EGR pipe as far as possible,throttle body refitted.
Battery connected and hey presto she starts and runs

Since the pipe clip bolts/nuts were not 'in safety' (ie nut flush with end of bolt shank) I also put a blob of paint on the bolt tails which hopefully will prevent vibration loosening off the nuts LOL.