Original birth certificate too new? section 3(1)

We would like to register our 2 children as British Citizens, born before 2006 in the EU to a British father (who himself was born in the UK) and a EU mother.

The UK Border Agency page states:

Children born before 1 July 2006 whose father is a British citizen but not married to their mother - section 3(1) applications

To be satisfied of the child's paternity we would usually expect you to provide:

a birth certificate issued within one year of the child's birth naming the child's father; or
any other evidence such as DNA test reports or court orders relevant to paternity.


So, now comes my question - we don't have the original birth certificate for one of the kids, the certificate we do have was issued 3 years after the child's birth.

Is this a problem?
If it is, how could we get around it?

Thank you very much for your help!