Hunter 22 Headroom
Not sure about Liberty 22, but the slightly later Liberty 23, has 58" in the centre
of cabin reducing to 56 forward.
Am toying with the idea of buying one myself. I'm quoting from a recent UK "for sale" .
Not quite sure if I'm allowed to paste a link to it though.
There's a Hunter Liberty Owners Association which could provide more info.
Hope this helps.