In an interview with the UK's Jewish Chronicle, Rav Bar-Hayim explains that it's permissible for Jews in the UK to eat kitniyot:
His reasoning is that the tradition of avoiding kitniyot emerged at precisely the time that Jews were expelled from England - 1290 to 1656. This means that, just as the kitniyot custom cannot be considered native to Israel, it cannot be considered native to England.
The tradition became established in England, he believes, by Jews who moved from Europe continuing to observe it out of habit after they immigrated. But he argues that according to halachah, when arriving in the "halachic virgin territory" of England they were free to either retain or discard the tradition. He believes that immigrants to England were unaware of this choice and therefore their descendants are free to either retain or discard the kitniyot custom.