Why on earth would there be a rule that a nanny can't share the same mother tongue as a parent? I'm guessing that the restriction on only allowing EU,US,AU,NZ etc is because they probably don't want nannies with dark skin or heavy accents, or (gasp) those with headscarves, but what's this mother tongue thing all about?

Or perhaps you are right, probably just part of the conspiricy to keep mothers at home.