Any episode I was involved with it was shot in darkness but some locations, I recall a prison in Aberdeenshire, insisted that security lights stay on because the stairs were a death trap. The nightvision green tint was actually built into the cameras that were used. So I can vouch that it was sometimes pitch dark during filming. They do use a grey filter over the green in the new episodes for some reason.
There was very much an unwritten rule with the show that if someone proved to be more popular than Yvette. Derek, Richard Felix, David Bull, even her own brother, Rick were all chucked from the show because the fans really liked them. There was a new medium during my time on the show, she was lovely, an American woman called Johnnie and it seemed very likely she would get the job full time. She was very funny, very talented as a medium and just a good egg but the problem was the fans went wild for her so she was dropped almost instantly. One of her best moments was when she asked for a spirit to throw a stone at Yvette and you saw Yvette was annoyed and said "Why say throw it at me?" and Johnnie without missing a beat replied "Because I don't want to get hit!" She would have been brilliant if she got to stick around.
I think that's what they missed when Derek left was the showman character. Gordon Smith, David Wells, Brian Shepherd, Chris Conway all brought their own thing to the show but Derek left very big shoes to fill and no one ever managed. Johnnie might have been a close second if she was allowed to stay.
Pendle Hill was the best show they ever did, sadly I wasn't there at the time but I remember watching it live. That was probably the first show where you could start to see cracks in the team. It's not as well remembered as the second night at Tynedale Farm but on Night 1, Derek picked up on what he said was a ghostly alien and Yvette went mental at him and told him not to say anything like that ever again