I was looking this kind of thing up today and even phoned the Isle of Man Immigration people as I wondered about the Isle of Man and UK Citizenship. Turns out that they are one and the same. So a child of ours born in the Isle of Man would have a British passport.

Quote Originally Posted by Terpe View Post
Source:-
BN4 - BRITISH CITIZENSHIP - CHILDREN BORN OUTSIDE THE UNITED KINGDOM SINCE 1 JANUARY 1983

For some strange reason, in this instance, the UK includes the Isle of Man.