Thanks for your reply and for offering some ideas. The layout is my Dad's, and having long since given up his garage, he's looking to outsource the frameworks and baseboards, preferring to focus on the track setting and scenic side of the hobby.
Thanks also for your observations regarding Dad's layout design. It is based on a US branch line, where he's modelling the California coastal area. The 'wye' triangle is a common feature of US layouts to aid in turning the locos around (if needed). This is his second layout after he learned a ton of lessons on his first, and so he wanted to focus on what first drew him to the US layouts, which was those expansive prairie scenes. Very peaceful. He's using the sidings for the occasional bit of freight that might happen. But I like your idea about flipping the station. I'll have a noodle later in Railmodeller.
Totton would be quite an undertaking! I'm often travelling through Eastleigh on my way to London and lose myself in thoughts of what the yard there must have looked like in years gone by. That's a fair size too!