Isaac Birk was my paternal grandpa from Lithuania and his aunt was, I believe, Anna Hinda Mitav who married Isaac Chazan and settled in Manchester, England in the late 1880s.
Under the Jewish resources on Cyndi's List, one of the categories is "Societies and Groups." I scrolled and clicked until I came to the Jewish Genealogy Society of Great Britain. There I found a link to the search page for United Synagogue Marriage Authorisations--a recently-updated index to rabbinical marriage records from 1880 through 1901.
Interestingly, both my grandpa Isaac and my grand-uncle Isaac had brothers named Abraham. But I never knew the maiden name of Abraham Chazan's wife Betty, and I hadn't checked records again for more than a year.
Then yesterday, I plugged in Abraham's full name, his wife Betty's name, and the year of their marriage (1895, which I knew from BMD records in UK). See the word NEW? Now I have Betty's maiden name, Matz.
So Tuesday's Tip is try, try again, because new records appear online every day.