In modelling - as in much of life, I suspect - the secret is to cheat where you can get away with it.
Which in this case is the black lines which divide up the blue panels on Britomart.
Why free paint them when you can use some nice, thick black waterslide lining?
This devious plan means that we get perfect straight edges to put the white lines up against to complete the little beastie's Great North of Ireland Railway livery.
Of course, at exhibitions, it is almost invariably identified as 'Thomas' by some of the younger visitors....