I guess all you need to submit will be your expired UK passport, as this is not an application for a first passport. Your expired UK passport is proof that you are a British citizen and should suffice as evidence of your nationality & identification.
On the Britainusa site, please check:
http://www.britainusa.com/sections/arti ... 01&a=25302
Below - a copy/paste of the link above
To renew an expired or existing passport or a passport that has no blank pages
You should complete Form C1
For a child under 16, you shold complete Form C2
You must send your old passport (it will be returned to you.) No other documents are normally required.
A parent’s signature is required on a C1 application at Section 9, if the child is aged 16 or 17, as well as the applicant’s signature at section 10.
If your passport contains visas valid for countries other than the US, Australia or Canada, and is still valid, it may be cross-linked to the new passport. Please indicate at Section 8 if you require this service (For cost, see 'fees' on main page of website).
If you passport has been lost / stolen or is unavailable you must provide the address at which you were living when the passport was first issued, the next of kin details included on your previous passport application form and the name of the person who countersigned the original application. For additional identification purposes please send your US passport or an enlarged clear copy (front and back) of your US Alien Registration Card and driving license (if held).
If you are a tourist, please supply a copy of any identification you may have (e.g. driving license, credit cards etc.)
There is an additional fee to cover the administrative cost of a verification check with the office where the lost/stolen passport was issued unless it was issued in the US.
The loss of a passport is a serious matter and there may be some delay while enquiries are made before a new passport is issued.
To renew an expired or expiring passport or to obtain a first passport for a person over the age of 75
You should complete a United Kingdom Passport Service application form which you can obtain from our office.
You must send your old passport (it will be returned to you.) No other documents are normally required for renewals.
If this is a first time application:
You must send a full original birth certificate showing full details of both parents.
If you were not born in the US you must send the passport or travel document that you originally traveled on to enter the US.
If you were born outside the United Kingdom, you must also send documentary evidence of your parents’ claim to British nationality i.e., their original birth or registration certificates and their marriage certificate showing the marital status of both parties at the time of the marriage (with evidence of termination of previous marriage(s) if applicable). If your birth was registered at a British Consulate or the Home Office, the original certificate is all that is required.
For additional identification purposes, please send your US passport or an enlarged clear copy (front and back) of your US Alien Registration Card and any other photographic identification.
