Hi Carole
Thanks for your reply. The older sister was my wife's mother, now deceased. We have Florence's birth certificate which shows a name change added after registration so Florence Peggy Edwards and Peggy Hayes Edwards are one and the same person - both have the same GRO reference number too. The older sister was brought up by her grandparents but for some reason they didn't take Florence and she went into the orphanage.
I'll have a look for a marriage - though she may not have known her birth surname or even, in those days, that she was adopted.
Hi Rosie - yes, that's her - dob 4/10/1921. The birth cert also carries a note that she was adopted but no date for the addition of this note.
Best wishes, Chris