**snip**
Toilets and waiting room are going to be needed at any time people are changing, including when they are changing onto and off the branch in the evening. I noted when we got back from St Ives that a number of passengers walked up to the station building, but staff (train crew) directed them up the ramp onto the main platform and around the outside of the shut building.
**snip**
St Erth Station: identity crisis, right there.
(OK, it has a couple of other crises as well, including a 'Suspended-on-hinges station name signs in need of oil' crisis.)
It's now a park-and-ride site, with a railway station attached, and the two haven't quite been brought under the same roof. Away from railway stations, and ignoring that one near Oxford that was built and then had no bus services for years, it's not unheard of for park-and-ride sites to provide loos, accessible loos, babychanging facilities, but this being a railway station, the parking is managed by
APCOA▸ who don't involve themselves in toilet provision.
While rail travellers might find the station loos closed, they have the option of on-train loos on the main line. In contast, for people using the site for park and ride, transferring from the train, provision of toilets in cars is notoriously poor - and if they're on the train back from St Ives, the number of loos on the train won't match the number of people needing them - and if they arrive at the site on the bus, buses do not have loos in the first place.
It would be good to hear an account of the visitor experience for people using St Erth as a park and ride for St Ives versus the historic experience at Lelant Saltings. The latter's weaknesses were 200 spaces vs 500 and a platform that was very exposed to the weather - but it did offer relatively straightforward transfer from car to train, and didn't charge for parking. Wikipedia has the history of the park and ride there.
https://en.wikipedia.org/wiki/Lelant_Saltings_railway_stationMark