It's a long saga, but the UK wouldn't renew my UK passport until it matched my US passport. UK had first and last name, US had first, last and middle initial. UK wouldn't add the middle initial unless I changed my name by deed poll!! And US wouldn't change the initial to my middle name unless I went to London with my birth certificate. By some miracle (actually by refreshing the screen every 2 minutes for nearly 3 hours) I got an appointment and went there yesterday and now it's done. When I get my new US passport, I can send it with my birth certificate and marriage certificate to HM Passport Office to get my renewed (not first, but renewed!) UK passport. The names will match, showing first, middle and last names.
WHAT A FAFF!