Thanks to Mr Le Roux' very keen eyes, more work on the tyres. Before and after shots of the tyres after removing the moulding ridge with a Dremel (Proxxon actualy) sanding disc. Then darkened the wheel rims between the tyres:
Fabrice - you were spot on as ever. The tank does now "sit" much more convincingly on its tracks, so many thanks.
Last bits and pieces to do before the Open Day. Today, I installed one of Thomas Benedinis water smoker cards. It does what it says, produces a very distince puff on acceleration and produces a good volume of smoke. Makes a lot of difference also using a centrifugal fan. I made up the smoker with a new enclosure, photos to follow.