It turns out that the "rails-vault" as shown on the sales panel above is none other than "Rails of Sheffield."
The 218 (Sheffield to Bakewell : T M Travel) has a seasonal frequency uplift on Sundays from hourly to every half hour.
Because of the significance of these seasonal changes, you might expect Travel South Yorkshire to tell you about them.
Fat chance! Go on-line and this is what you find:-
There will be some bus service changes in South Yorkshire on Saturday 29 and Sunday 30 2017. Services that are changing will be shown in the list below along with links to the new timetables on Friday 7 April 2017.
But there is a non-leaflet for service 65 ...