Bertie's from a fairly obscure canon unless Mika is an Anglophone. Or if she's a big fan of her world's Hugh Laurie/Stephen Fry. In which case, she might have seen that in their acting credits. If either of these are true, she's welcome to know who he is.

We got some amusing mileage with another character in JJ vaguely recognizing him as Hugh Laurie. She's welcome to note that he's similiar in appearance, though I headcanon him as a liiiiittle more fair-haired than Mr. Laurie.