Norwood Orphanage was at 38 Knights Hill, West Norwood in South London.
There were (are?) several orphanages in Sevenoaks.
This link will show you two homes in Sevenoaks as well as the Norwood orphanage - http://www.formerchildrenshomes.org.uk/1900_orphanages.html.
You may already know that the STREATFIELD/STREATFEILD name goes back a long, long way in Kentish history.
This site will give you some idea: https://julietsgenealogy.org/my-family/streatfield/ -- and then you can click on "name index" and navigate to your surname.
In fact there are some very experienced STREATFIELD researchers, and I'll message you privately with the email address for Michael Jeffries, who I wrote to a couple of hours ago for you.
He sounds very helpful and quickly responded. He wrote, "It would be better to have as full information of her Streatfield ancestors back around 1880 to 1920 as this can reveal the links more quickly" - so when you correspond with him, please bear that in mind.
Gold Coast, Queensland, Australia
Not researching STREATFIELD, but had some ZAUSMER family at Norwood Orphanage, c.1905