Bit the bullet and signed up to O2 online yesterday. Since then I've had 2 emails asking for the same thing (driving licence or passport) both with a different number to call.
Yesterday it was 0800 977 7793 and today it was 0844 8471420. The guy today said yesterdays was a credit check, todays was ID security as there have been a lot of dodgy orders in my local area! I said I thought it would've been better for one call to cover everything as their emails could be considered to be attempts at phishing...

Last time I signed up for a new mobile account was with Orange in 2002. Has anyone else had to jump through these hoops?

Have you moved into your present address recently or have you got a restricted entry on your local electoral register? The latter is often one of the principal sources used to verify identity. Similarly, passports and driving licences mean that you are a real person (usually!!) as there is some form of government verification built into their issue.

Also, if you are in a property converted into several flats, it is not unknown for one resident to pretend to be another and apply for one in their name. As delveries are made daytime, there is a good chance somebody who commutes will be out so the impersonator can listen out for their door calls.

We will have been in this house 3 years this coming November.
I can understand them wanting to check people out, especially with the order having been made online, it's just that the 2 different emails on the same subject from 2 different O2 email addresses wanting me to phone 2 different phone numbers came across as a bit dodgy to me

Why not phone O2 and ask them? At least when you call, you know it's really them. Their sales team will be eager to help you open an account!

Agree, find the number yourself and you phone them.