London Gazette has something, 20 Sep 1940; list of aliens to whom naturalization has been granted:
Schurmann, Margaret Babette; Germany; of no occupation; 20, Highfield Gardens, NW11, 5 August 1940. The record is marked with '*', denoting it as a 're-admission to British Nationality', indicating that she was previously a British citizen but had lost that somehow - usually by marrying a non-british man. If this is her, I'm not sure why she's going by her maiden name or if that's just usual but it seemed too much of a coincidence to ignore.