Question about history of British Jews

My mother’s great grandmother (her patrilineal side) was Jewish and so was her family. They emigrated to Australia (Southern New South Wales), from the UK in the 1880s (I believe) and had the surname Whittaker (I believe this was an anglicised surname). The Judaism in the family was lost when this ancestor married a Catholic and possibly converted to Catholicism. My question is, were British Jews in that time period Ashkenazi or Sephardic or something else? Thanks!