Sex scenes were a whole new ball game for Rhys Thomas who plays the emotionally challenged Stuart in Sirens...

"Oh god. The naked bits, the nude scenes, I've never had to do those before,' he shudders. 'I had to do the sex scenes on Valentine's Day which was terrible. I had about four scenes and had to wear a modesty sock which was weird. It was completely nerve wracking and I was so glad when it was over. There is nothing remotely sexy about those scenes but it felt slightly wrong doing them, even though there were about eight blokes in the room fidgeting."

But that possibly wasn't the strangest encounter Rhys had during the production process... "I spent a night out with an EMT (emergency medical technician) unit as part of my research and we were called out to a woman who was in labour. There was no time to get her to hospital because this was her fourth baby and it might have been born on the stairs getting out of the block of flats. It was weird because I'd been in a similar situation with my own wife and there I was in a yellow jacket looking part of the team so I was calming down the mother-in-law. The baby's father seemed more worried about the rugby results and whether she'd make a mess in their bed so he was trying to get them to deliver the baby on the wipe clean sofa. It was an amazing experience to see what they go through in a night. I have loads of respect for the ambulance service."

Describing his character, Rhys says: "He's quite a misanthropic character, quite miserable a lot of the time and not very good with people, especially women. His dad left when he was 13 and he just never really got over that. As an EMT, Stuart wants to help people but he feels so let down by humanity. So disappointed that there are so many idiots around; drunks who he ends up ferrying around when he should be helping people with real problems. He is fed up with all the 'naked apes' - the people out on the streets of Leeds on a Friday night getting drunk, fighting and having accidents. He's very mixed up but he is good at his job. He's a bit of a know-it-all and takes lots of chances. Stuart will always be the one to take a risk even if it's not protocol. He's like the kid in class who is really clever and feels he doesn't have to concentrate to get it right. He doesn't like the bureaucracy; he'd rather be out there doing the job."

So why is Stuart an EMT? "We find out that when he was a little kid he had an accident which resulted in a crossbow being shot through his shoulder. A paramedic turned up in his uniform and Stuart saw him as an heroic figure; someone who came along and saved him. And he thought 'that's what I want to do'. His drive to help people is genuine even though he might tread over a drunk to get to a real victim. He does care about them if they deserve it."

"Stuart hasn't got much else going on in his life, his work is his life. He doesn't really have friends outside work except Maxine, a friend from university who is a police sergeant. They are best friends in fact; he talks to Maxine much more than Ashley or Rachid. Maxine is the one he confides in as she does in him. You can't tell if he fancies her or not - maybe he doesn't know. Their paths cross a lot at work because police are often at the scene. And there starts the rivalry between Stuart and Craig the fireman. Maxine becomes friendly with this fireman but firemen and paramedics don't get on at all; there is a natural rivalry there. Firemen tend to be heavy handed, the tough guys smashing windows and pulling the roof off cars while the paramedics stand there waiting to look after the people who are hurt."

"Does Maxine like the fireman? Does Stuart fancy Maxine? Can Stuart come to terms with the fact that he might fancy her - this is real will-they, won't-they stuff. Stuart wants to control his feelings. This is a major issue for him. Since his dad abandoned him he has no faith in relationships and can't trust his feelings. He doesn't want to feel lost in love."

"One episode is about Stuart having a girlfriend which is really unusual for him as he doesn't want to feel emotional on any level. But he fell for her and it reminded him that there is more to life than being cynical. More to it than thinking we're all just animals, we're all going to die so just make the best of it. That is his defence mechanism. He actually says, 'I don't allow myself to have feelings in that way' because he's built up walls and that's how he survives.'"

"I do identify with Stuart in some way. He is a grumpy old man while still a young man, and there's a lot of that in me. I try to bring a bit more of myself to Stuart to make him more likeable. But I can see the good in him.'

And is Rhys cut out to be an EMT? "In terms of what we do as a living there are some similarities. As an actor it's not a 9-5 job, you never know what'll come up or what you'll be doing one day to the next. With the ambulance service that's what they like the thrill of not knowing, living on adrenaline, thinking on your feet. Also at times they have to act in front of people to make them feel at ease even if the situation is terrible. I really admire what they do but I'm too squeamish. I couldn't do it."

And he might have some issues driving the ambulance... "They were always complaining about my driving on set. I thought I did all right considering I've driven an automatic all my life. One day we were filming at an old people's home and I had to reverse through quite a narrow entrance into a car park. The guy from the company which owns all the vehicles wanted me to practice but he was always nagging me about my driving so I said I didn't need to and just got in and started reversing with the camera in the cab with me. Then I heard this awful scraping sound and everyone laughing at me. It wasn't till I got out that I saw I'd knocked down an entire wall. It was like Some Mothers Do 'Ave 'Em . After that they got stunt drivers to reverse the ambulance because they didn't trust me..."

Rhys is not a man to sit around and wait for a job. "I don't like doing nothing," he says. "I couldn't sit and wait for the phone to ring to get a job. That's why I write and produce - I love Queen so produce documentaries for them and write sleeve notes - that's just for fun. Writing I consider my main job because that's what I enjoy doing the most. But last year I did a show called Bellamy's People, a spin off from Radio 4's Down the Line, which wasn't recommissioned so I wanted a break from comedy and wanted to prove to that I could do something different. I'm used to improvising, making up my own lines and being involved in the whole creative process from beginning to end. With this I do exactly what I'm told and it's nice to come to work in the morning knowing the lines that have been written for you, going home and learning the lines for the next day. Not having to worry about the rest of it. Stuart is very well written, a gift of a character."

Rhys is married to the comedian Lucy Montgomery with whom he works on the Radio 4 comedy Down the Line. "My wife is one of the main characters on Down the Line. She is genuinely funny and can do any voice or accent, she really makes me laugh. It's nice working together but harder now we have two children."

Rhys won Celebrity Mastermind in 2010 with Queen as his specialist subject. He has recently produced a Queen documentary for BBC2 but sadly for Rhys his wife doesn't share his taste in music. "I tried to get her into Queen but it really hasn't worked. I even took her to a Genesis concert because I love them but she kept going off to buy hot dogs..."