My input was to scratchbuild an overall roof from styrene strip, section and sheet. I kept the design pretty simple, suggesting an austere - perhaps post-war - structure to suit the 1960s vibe. Building the roof 200 miles away from the rest of the layout meant that I had to take care with the measurements. And even greater care was needed to carry it down to Peterborough on the train!!
Thankfully, it made it in one piece. And it fit perfectly.
The project appears in Model Rail magazine issue 269.