The Gorse Fox has just got back from Chi. A minor upgrade to the mobile phone plan was achieved, and advice on how to cancel residual plans on second phone and iPad.
GF also popped in to the Apple store. On their advice, he has resorted to the sledgehammer approach. Still attempting to clean up his iPad he has just done a complete factory reset. No doubt it will take a significant time to restore - but hopefully this will clean up the junk data that is evidently hanging around. The reset is complete and the restore has just begun.
Several tens of minutes have passed. The iPad seems to have been restored and the apps are re-syncing. The 22GB of wasted space has dropped to 5GB. That seems like a result... at this stage. The minion in the Apple store suggested this may also speed up the iPad - one can only hope!