In the last year coming back to UK through both Heathrow and Gatwick, there are signs up saying "IRIS is closed today". Even though it's not, and I walked through it fine.
In T5 in October I went to check I was still registered and two of the surliest, most humourless people I've ever been dealt with by in my life, handled my query efficiently, whilst at the same time ensuring I never wanted to do it again. EVER!