Hello Stone
I just wanted to thank you again for your help - and to let you know that I have had Alice's birth certificate and the parents are Richard Dennis Cooke and Anne Cooke formerly Burke.
So I have come to the conclusion that Richard and Denis are indeed one and the same person and that Anne née Burke, his wife and the recipient of the letters, was really called Bridget and, for some reason, used the name of Anne (which could be her second name as she has a sister Mary Anne). This is the only theory that fits.
Regards
Tilly