Felt like I'd done about ten rounds with Tyson afterwards but I think it went okay. There's a second interview next week and I'll find out later this week whether I've survived this stage or not.
Thing is though that the harder they make it, the more it makes me want the job. Very good potential earnings, very good future prospects, very good training and qualification opportunities.
Need to forget all about it now and get on with applying for some other jobs.