Hi
If she lived in Shepherd's Bush this would probably be the most likely marriage for Ada Matilda
Marriages Sep 1916
Clark John D Stanton Hammersmith 1a 526
Stanton Ada M Clark Hammersmith 1a 526
Harder to track Emily as she only has one Christian name but if she lived in the same area as Ada this could be her.
Marriages Dec 1919
Parish Albert E Stanton Hammersmith 1a 780
Stanton Emily Parish Hammersmith 1a 780
If they married at St Paul Hammersmith those registers are held by Hammersmith and Fulham Archives.
Wembley the London district is about 5 miles away from Shepherd's Bush so not exactly close by but not far away either. Again it might be worth contacting Hammersmith and Fulham Archives about girls boarding schools in the area as there doesn't seem to be anything easily found on a Wembley School.
These are the schools they hold records on, but they are less likely to hold records on private or charitable boarding schools.
http://www.lbhf.gov.uk/Directory/Leisure_and_Culture/Libraries/Archives/23452_Records_of_Schools_and_Colleges.aspRegards
Valda