The rights have been asserted statement, in various forms, sometimes just saying the moral rights gave been asserted, is in the four novels I have just taken off the bookshelf.
Only one made statement about characters being fictitious.
All had the not in any other covering statement.
The moral rights statement is not one I remember always seeing in books, it just seemed to appear relatively recently.
No, it just has "Copyright the estate of John Wyndham".
I must go back and reread my John Wyndham, haven't done so for many years.