I'm still working on it, but there's not much to go on at the moment.
If you did want to go deeper into the search, you could buy Jonty's marriage certificate. That would give his age for a more precise date of birth (and father's name) and may match with the tree Cas found (or not). I can't see the age from the index. If it does match the tree, you have your answers. If it doesn't you have more information than you started with at least.