Two-time Oscar winner Peter Ustinov is considered one of the greatest British actors ever. Just look at that stiff upper lip!
But Ustinov's heritage is not exactly British. It's actually... Israeli? Well, Palestinian, at least, as his father Jona von Ustinov was born in Jaifa. Jona as an interesting figure in his own right: he spied for the English in World War II.
But Jona's heritage is not exactly Israeli either; his father Peter was a Russian baron who converted to Protestantism and opened a hotel in Jaffa. No, he didn't convert from Judaism, so if you're looking for Jews (as we tend to do), you hit a dead end there.
To find Jews, you need to explore Jona's mother, Magdalena Hall, who was a daughter of an Ethiopian(!) lady-in-waiting(!!) and a Mortiz Hall, another convert to Protestantism who spent time as a cannon-caster(!!!) for the Ethiopian king(!!!!). This time, the conversion came from Judaism, which makes Peter a whole 1/8 Jewish.
To summarize, Peter did not have an ounce of British heritage in him. That stiff upper lip is imaginary!