Help!! How do I prove I'm British?

I was born in 1987 to a British father and Canadian mother who were married since 1982. I cannot get their marriage certificate as it was issued in Kenya and they can't find it! My mom also only has one copy and absolutely refuses to part with it to the point that she isn't speaking with me now. My father died last year.

This is what I have:

Birth certificates for my mother, father and myself.
Death certificate for father.
My parent's jointly filed Will
My father's Army pension number (from Britain)
My parent's deed on the house they bought together in 1987.
Affidavits from three family members that they were married for 31 years, notarized.

Is there anyway I can get my British passport with special consideration? I simply cannot get a marriage certificate. If anyone knows how I can get one from Nairobi Kenya (where my parents were married) I would be extremely grateful. The embassy in Washington DC couldn't find it.

Ask your Mother for a copy of the copy?

Also contact 020 7636 2371/5 and ask if they can help.

Thank you for the High commission number.

I think I will have to get a copy and have them certify it.

If I cannot obtain a copy, I'm not sure what I can do. But I'll cross that bridge when I come to it.