That's it - House of Lords - Iolanthe - Gilbert and Sullivan - Pirates of Penzance.

There's the answer:
He is an Englkishman
For he himself has said it
And it's greatly to his credit
That he is an Englishman

For he might have been a Roosian
A French or Turk or Proosian
Or perhaps Italian
But in spite of all temptations
to belong to other nations
He remains an Englishman!