Just a note on the re-routing. This was due to the landslip at New Mills Central resulting in single line working through there making pathing the excursion problematic. This has meant routing the Sheffield - Piccadilly stoppers via Stockport so the service through Marple is now hourly. The remedial work is expected to end by May 7th. I think this is optimistic as the site is problematic.
I'm surprised it ran considering it was midweek in school term time. Ironically when they ran on summer Saturdays the weather was often rainy meaning thick cloud over Mam Tor and the windows were steamed up anyway whereas weather on the 17th was quite good given all the bad weather.