Best way to send a passport back to the UK?

[Viper_Larry]

I need to renew my UK Passport whislt residing in the US. Easy to do via the web, just need to get the photos done and send it off. Question is, how should I send it as so far, everything I've looked at seems extortionately expensive! UK Passport office want an equivalent $15 fee to send back to me by courier, but here prices are from $50 - $85 to send it? Surely there's a cheaper way. No particular hurry, but I do want it to be secure, and it weighs barely nothing...

Any recommendations?

[Viper_Larry]

I've been using the British Passport's online service:

https://www.gov.uk/overseas-passports

SHould I not use this? Looks like it's a new way to renew from abroad?