I renewed mine from the USA and I used FEDEX with no problems.

I used USPS Flat Priority Mail International Flat Rate Envelope which, like UPS and FedEx, tracks the whole way and requires a receiving signature.

You should be using your US passport to leave and enter the US anyway.

FIFY

Thank you everyone for your advice and contributions. I ended up renewing as an overseas candidate. It took 2 days to get to the UK via FEDEX and within 2 days the passportapplication.service.gov.uk went from accepted to dispatched and I received both old/new passports 2 days later. 1 week turnaround !!

Wow, that's awesome.

Since many of you have recently had successful passport renewals I was wondering where you got your pictures taken? Did you use a grey background or a white one? Did you send US size pictures or UK size?
All of the posts I have seen on the matter are a couple of years old now so I would like updated information. Thanks!

Look for threads including the word "passport" and there should be at least four this year discussing pictures - I know because I renewed my passport in the spring and have discussed pictures at least four times since then, and quite possibly half a dozen times.

Some people report that some Walgreens can do UK spec pictures, as apparently can AAA. I just got US spec pictures and cropped them by hand to the UK's required dimensions. My passport took eight days to come back (sent and received in the UK).

Walmart, white background, US size. Not an issue.

Ian

My wife renewed her UK passport a few months back. She got EU size passport photos at Walgreens.

Picture taken at home on plain cream background, printed at costco using epassportphoto.com. Cost all of 20c. Can produce UK or US sized photo. This was last year.