Graham Boak

 Hunbrol used to do Track Colour, which I once bought for model tanks but soon learnt otherwise.  It hasn't been available for some time but is being re-released this year (if it hasn't been already).  No.173, but it isn't showing on their colour pages yet.

EDIT:  Yes it is. http://www.humbrol.com/shop/paints/enamel-paints/?page=15     160 German Red Brown might be a useful colour if you want a brighter rust.

I used to go to the aviation side of Motor Books - is that still going or has that folded too?

Aircraft modellers have a useful category "What If" which would seem to cover most of the ideas above.  For NER enthusiasts, how about an electrified main-line providing a useful home for re-liveried HO Swiss Crocodiles?  Is South Farne reached by bridge or ferry?