I visited the IRIS office at LGW North at the end of January which was manned and open.
I keep failing to persuade IRIS I am who I am so I wanted to check whether I was still registered. They suggested I try the new picture comparison machine, which I did on the way back and that worked perfectly. Maybe IRIS is to be phased out in favour of this new system?
(I'd really like them to introduce a fingerprint scan like I use when entering or leaving HK - that is damn quick)