A photo from the Carnforth (I think) section of my collection. Possibly the smallest Midland Railway style signal box.
Midland boxes were a modular design. According to the Internet, this is a 4A version.
The box was moved to the now closed steam centre from Selside, Horton in Ribblesdale. Sadly, it's current state of repair is rotten and falling down. My photos from the 80s show it in a far better state.
Modelling a box like this wouldn't be too hard. Start with the windows from Ratio and some Wills clapperboard. The rest is reasonably pleasant scratchbuilding. Far easier than the job I had building a half-decent model from the Airfix kit for Hornby Magazine's Topley Dale. Sadly, Airfix got the window proportions very, very, wrong and fixing them would have been a lot easier if the brief had allowed me to throw the kit away...