aaanjoo, the difference is not so much whether the child personally has ILR, but where they were born. If child born in the UK :-
- if born after one or both parents has their own ILR, then child automatically British from the moment of birth, but
- if born prior to both parents getting their ILR, it is necessary to apply for registration as British using form MN!, but no ILR compulsory when making that application
Consider this list, in order, which could actually happen (although admittedly the timescale would usually tend to be a bit longer!) :-
- child is born on Monday
- on Tuesday one or both parents get their ILR[(at a PEO)
- on Wednesday the birth is registered, so a birth certificate is issued
- on Thursday the form MN1 is posted!
The point is this. The child does not have a visa, or indeed a passport, but nevertheless an application for Registration as British can still be made.