Thank you for your helpful posts, ladies! Isabel(la) is quite an enigma. The "St. John Mildmay" line is an old one with at least one long-term home base in Wiltshire. In Victorian times they do seem to have been into the diplomatic and military services, which spreads their records out a bit.
As regards "Clement":
I have just found a birth in the Consular Birth Returns 1849-1854 for an Edmond Clement ............ Mildmay in Frankfurt. This might be Isabel(la)s father.I see that the "William Montague" in the 1881 census entry was born in Germany but a British Subject. Was that fairly common, I wonder, or is it significant?
As yet I can find no marriage for him in the FindMyPast foreign indices, on Scotland's People or at the GRO.
There appear to be two deaths in the GRO death register which are contenders: the one in 1881 Q4 Kensington to which the Tooting burial refers (thank you, Tati) and one in 1889 Q3 Kensington for an Edmond C. St. J. Mildmay (age 31).
Isabel(la)s son was given the names "Edmond George St. John" - I don't know if the spelling is significant.
Contrary to my post I don't have Isabel(la) in the 1901 census (I should not try to proof my posts without putting on my reading glasses - sorry!). She married George Henry Stevens in January 1900 and I have searched for both of them in the 1901 but not yet found them.
I think I shall have to order the birth certificate of this "Isabel Montagu" you found, Tati, just in case the name was mis-entered in the Birth Register, or if the family were using "Montague" in preference to "Mildmay" (if they weren't married perhaps this was done for the sake of the Mildmay family honour). It seems the most likely contender so far. Perhaps this would account for why Isabel(la) and her mother only used "Mildmay" later on after the head of household's decease. And why later on should one move ones place of birth from North to South of the River? Unless one were trying to cover ones tracks ...
Rachel
