Can anybody actually confirm whether they have to be included in the application and also if they do need to be translated as there is no clear indication in the guidance notes for form MN1 for children's UK citizenship ???

As I originally told you; yes and yes.

From The documents we require for registration as a British citizen by a person under 18

You should provide translations of any documents not in English.

][/b]Evidence from children living in the United Kingdom

You should provide:

• the child's full birth certificate; and
  
• the child's passport used on entry to the United Kingdom and any other subsequent passports; and
  
• the parents' marriage or civil partnership certificate.
  

The same information appears on pages 29 and 30 of Guide MN1

I agree with 7by7. This is all true. Friend did the same last year.