Re: It's all in the 'title'
The passport office website says, inter alia, engineer with professional qualifications, photographer (professional) and travel agent (qualified). It seems more about identity than your actual job.
Apparently the BCS membership and the BCS CITP counts too.
Bizarre, I think I got my CITP free with a packet of corn flakes. Costs me £200 a year for the privilege of knowing I am chartered, but no one has ever shown any interest in it and I think I got it simply by saying I'd done stuff.
A quick google around shows one anonymous random person saying that they checked with the passport office and the passport office accepts a CITP https://www.certforums.com/threads/bcs-affiliate-passport.36357/