Temporary British Passport Records

[Fide et Fortitudine]

Where could I look for and/or get a copy of an Emergency Certificate of British Nationality issued to an Italian national in 1922? 

[jorose]

If such records survive, the most likely place would be the NA in records of the foreign office (FO):
http://discovery.nationalarchives.gov.uk

I would first just search on the name (or just surname) - you might be in luck as some of their files appear to have been more fully indexed:

Mrs Léonie Simon, resident at Namur: application for an emergency British passport (form with photograph in docket no.144728), and enquiries about her nationality.