Parky,
I think in the end I had a bit of a gap at the front edges of the sides of the bunker, but covered these with some waste etch strips. I'll check it tomorrow.
By the way I have lots of photos of both DoS and CoB, and provided you ignore the preservation features on DoS, are useful references. CoB is in BR condition but is of course a de-streamlined version, but apart from the split running plate it's still a very good detail reference. If you need anything on that let me know and I will post any photos that may assist.
Simon,
Thanks for the comments on lead shot and PVA. It's because of the issues that occur when PVA breaks down liberating acetic acid, that I thought I'd try a dry approach, particularly as the Duchess is painted. I'm thinking that with a fabric tube, the lead will be retained, will settle to the shape of the boiler and can be easily removed in the future if desired. I'll post some pics on my own thread when I get around to doing it.
As to lead shot, according to the DCC concepts website, it is becoming more difficult to get hold of due to restrictions on selling it by gun shops. Don't know about that, as it seems readily available from various sellers on ebay for use as divers pouch weights. The stuff I've bought is about 2mm diameter so should be just fine and is less than half the cost of liquid lead.
Sorry for the hijack Parky.
Cheers,
Peter