Use example of an aristo I used to encounter once in a while. Aged 80+ and with far too many relatives and friends for even a young mind to keep track of, her standard MO was to sweep up to absolutely anyone and say "darling, who ARE you?" Done with sufficient charm, it works every time.

I should point out that, on more than one occasion, the response was tears and "don't you remember me, Great-Grandmama?" But she remained serene and it all passed with time.