Visible rivets on smokebox wrapper plates

[drmditch]

I'm just starting a J21 project (which I will eventually post on my thread in the modelling section.) My chosen period is 1947, and I thought that Darlington started using snap-head rivets on the smokebox under BR. However my morning browse of Yeadon 47A reveals that some appear on late LNER examples.

I would be very grateful if anyone could advise me on Darlington works practice as regards rivets, and when it changed.

[silverfox]

I am building a 5in gauge B17 and this class is a smokebox minefield. B17s had smokeboxes with flush rivets on front and rear rings, mushroom head rivets on front and rear, mushroom head front flush rear and vice versa, and two different smokebox doors. My loco is the smaller GE type door and rivets front and rear, at the time i intend to model but no doubt someone will come up with photo evidence i 'have got it wrong'
It really depends on how true to loco you want to go.