Deux, trois, quatre... "sink"?

I explained to Frances that the “Cinque Ports” were, originally, a cluster of five ports dotting the south coast of England, established and reinforced by the Plantagenet kings in the thirteenth century to protect the realm from sneaky and persistent French attacks. The ruling class in those days, descended from William the Conqueror, spoke mostly French, and “cinque” had been derived from the French word for “five.” Even so, no attempt at French pronunciation was ever made or even countenanced. It just wouldn’t be cricket.
“So a ‘cinque’ port becomes a ‘sink’ port? That’s odd,” said Frances.
“Odd? Doesn’t sound odd to me! English pronunciation of French – get it?”