Father's British passport number required

[Oompa Loompa]

Hello,

I am starting to fill in the application for my child's first British passport.
On page 2, Section 4 the form asks for the Father's British passport number, which I don't know and am not in the position to ask from the Father.
What should I state? I do have details of his previous passport but it has expired a couple of years ago.

Many thanks for your kind help.

[noajthan]

Hello,

I am starting to fill in the application for my child's first British passport.
On page 2, Section 4 the form asks for the Father's British passport number, which I don't know and am not in the position to ask from the Father.
What should I state? I do have details of his previous passport but it has expired a couple of years ago.

Many thanks for your kind help.

Do you have sole custody/responsibility for child?

You could state "not known" & explain why or quote the old number and explain why its old.

[Oompa Loompa]

I do have sole responsibility, thank you very much for your help!