Some days you have to wonder about old model makers. I mean with the prototype sheds still standing and available to look at, how did the Airfix model makers get the bricks wrong ?
For those who don't understand brickwork, the way the things are laid is called the "bond" - you can read more about it on Wikipedia here. Most railway buildings use what is called "Flemish Bond" where you see a mix of stretchers and headers (the sides and ends of the brick). The Airfix shed uses stretcher bond, a form more commonly seen on modern cavity wall buildings and never as far as know seen on engine sheds.
Worse the bricks are too big. They are probably suitable for S scale but not 4mm. Still, I can't change them now even if I could be bothered. Just goes to show though that not everything was better in the old days.
Anyway, I pondered this problem and decided to ignore it. Inside the shed will be 4mm scale Slaters Flemish bond bricks. &mm ones were considered but are just too big to match the outside. OK so they won't match the outside but I can't be bothered to worry about this and doubt that many people will notice anyway. Except you lot and that's only because I told you.