melmoth

Did you consider cutting the signal box down by a window bay? One of the possible pluses of GWR quasi-modular design when it comes to kit-bashing buildings.

And then there's the auto trailers with an entire alphabet to themselves...

The roof was removed in 1926  or thereabouts according to Brian Jackson's "The Abbotsbury Branch", but the only photo in the book which shows the roof of the shed is an incidental one, and the shed is out of focus in the distant background. It does however appear to have had a simple roof without any additional clerestories or similar ventilation.