Thanks for your replies. While I agree that it is unlikely single women adopted, we wondered if Glorie/Cecilia did marry, but not in the UK and was therefore a widow. We know she was using the name MONTGOMERY in 1916. She may have spent time in France/Belgium during the war, and could have met and married over there. Her husband if she married was probably killed. So by the time she returned to the UK she may have been a widow. (The name DE MONTI is very rare in the UK, but more common in northern France/Belgium.) We do know she was using the name DE MONTI in 1929/30 on the voters roll for Pitsea. She also named another child in her care DE MONTI, born 1930, but we know she was definitely NOT the mother. We have been in contact with this person, and there are differences in how they were treated. This is why we wondered if Pierre was adopted. But he just as easily could have been fostered. We have checked the births for Scotland and drew a blank.
Edward and Elizabeth consistantly used the name MONTGOMERY as far as we can tell. Glorie listed her occupation as a Private Governess/Teacher. Checking the adoption register is more about not leaving stones unturned, but it would be good to rule it out.
Lynn