Originally Posted by NWIFlyer

The most frustrating part of the online form is persuading it that the photograph is valid. Last renewal I submitted several with it insisting the background wasn't white enough no matter what wall I stood against, yet clearly there wasn't anything that went against the guidelines. So purely as an experiment to try and work out what was wrong (the Passport Office specifically says you can't submit using any sort of manipulation) I dropped a pure white background in via editing tools to see what would happen - and it still failed for the same reason. Certainly some phones and tablets are better than others at getting a tick so it's a bit of a lottery.

Fortunately you can override the auto-assessment and declare that the photo is fine. I went back to the original, did that and my application sailed through in a few days.

If you need a signature on your photo the process is much easier as well, and my profession means I'm able to verify them - it's all done online as well, just make sure you have a way of contacting your verifier because as I recall it asks you to confirm one piece of data you woudn't particularly know (indeed, HMPO suggests you do actually contact the applicant to check).