Final two digits of Child Benefit number

Horlock

Can anyone tell me how I could go about working out my old child benefit number? Or indeed any child benefit number?

OK what I've got in concrete is:

First three digits are: CHB
Next 8 digits are the first 8 digits of the 12 digit reference they pay it into the bank with.
Final two digits are: not sure

Is it possible that these last two digits are unique to the claimant - ie they don't change when your Child benefit number changes?

I have my current child benefit number but need to track them back to my first child's birth.

This is all to do with fact that it appears that I claimed child benefit instead of my wife. No one explained that it does matter who claims at the time we claimed, now I need to fill out an application form for Home responsibilities protection form and we don't know the child benefit number! Inland revenue have returned the form saying we must state it. I've phoned them and been told they can't help me.

I finally spoke to someone who did help - but sadly now I've forgotton what they said about the last two digits.