That was a clever move!
Unless I'm very much mistaken the only option left other than tracing our steps on the train, or waiting an hour for the next train forward, is to take Stagecoach South Coastliner 700 from Warblington Green Pond Corner (sounds lovely!), which is a 6 min walk away. However, we've missed the last eastbound one at 2028, and the westbound one at 2037 is too tight, so we await the 2137, alighting at its terminus in Havant Bus Station at 2140.
It's outside the rules, but we could have been there at 2047 if we'd walked all the way!!!!