There are lots of people who can lead hazops. It's important to ensure the person chosen understands chem eng broadly from practical and theoretical perspectives. Whilst it's not essential they are well versed with the technology under consideration, it does help.
The IChemE approved courses are good quality, but please remember they won't turn delegates overnight into hazop leaders! The best you can hope for from a course is to become a good hazop participant.
Trevor is a great chap, an excellent safety professional and engineer. I was pleased to meet him when he addressed a safety course when we worked for ICI - he is inspirational If he gives a lecture, go to see it if you can!
Hazard studies were developed by ICI originally, although it very quickly caught on around the world. Most people now only use Hazard Study 3 (aka Hazop), but there are 5 other stages that are equally useful!
However there are more books on the subject, and I find that thinking is advancing constantly at both an academic and practical level.