The Ladykillers, the play you wrote based on the 1955 film, has returned to the West End. What were the difficulties in transferring a film to the stage?

The hardest thing was getting rid of the bodies. One of the rules I set myself was that the characters shouldn't be able to leave the house. I broke that once – I let them on to the tracks [to get rid of the bodies] – and I'd rather we hadn't because I thought it would be a pure play in the house. It would also make it more theatrical to stick to this one room.

The film is thought of as a classic comedy. Is there such a thing as timeless humour?

That's a good question. I saw Some Like It Hot the other day. It must be nearly 60 years old and it still stands up but it's over two hours long and doesn't need to be. Certain scenes are over-explained. Our ability to process information – we can do that much faster now. Our expertise in decoding stories is such that you need very little to know what's going on. I don't think humour changes but the framing has.

Are we processing information more quickly because of social networks?

Everything affects how stories are told. So many people are using it and using Vine [a mobile app that enables you to share short videos]. People are doing seven-second comedy films now which are pretty incredible. It's a whole new vocabulary and one I love.

The scriptwriter of The Ladykillers, William Rose, is said to have dreamed the plot. Have you ever dreamed a sitcom?

No, nothing that involved. There have been times when I dream a joke and I wake up and it's something like: "A man sees a bush but it's not really a bush, it's a car." I had a tweet recently that came to me in a dream and did work [as a joke]. I stopped telling jokes on Twitter. I'll have to start again.

One of your best Twitter jokes was when you fabricated a rumour that Osama bin Laden was captured while watching your sitcom, The IT Crowd [Linehan tweeted: "Does anyone have confirmation that Osama was watching The IT Crowd in these home movies? Amazing if true. Don't know how to feel"]. What do you think he'd actually have been watching?

The Golden Girls. I can see him being a huge fan.

You have two children, aged five and seven. Do they think you're funny?

Yeah, they kind of do. You need to tune into a different way of being funny for kids. They're learning the rhythm of a joke. I've trained them to wait for the right moment to laugh so I'm never sure if they actually think I'm funny or they're just laughing because they know it's the right moment to do it.

Before the huge success of Father Ted, you and co-writer Arthur Mathews wrote a short-lived sitcom called Paris, which failed to get recommissioned after the first series in 1994. What happened?

It was about Paris in the 1920s and Alexei Sayle starred as a frustrated artist watching momentous things happen in the world of literature and art. It was in the days that I didn't realise writing was rewriting, as they say. We would refuse point blank to cut the script down to its proper length, so we'd end up with shows that were overlong. The other problem was we decided to paint the backdrops and, as a result, everything felt fake; it wasn't grounded in any way. It was all shouting all the time and once that kind of tone was established, all the actors would hit that same high volume level. The good thing was that it really gave me a shock. I realised I had to keep a very close eye on things. Every single thing was important.

You were raised a Catholic in Dublin. Did your family worry that Father Ted was sacrilegious?

After the first episode my mother asked all the actors: "Is it funny?" But after a few episodes, they were my biggest fans. They were a bit concerned it would be scandalous but we always wrote it in such a way that it couldn't offend people. We didn't do a lot of things you see in other ecclesiastical comedy, so we never saw the characters doing Mass – we broke that rule once because the joke deserved it – but generally we tried to avoid the cliches. All the satirical jokes were so silly. And it was in the days before the scandals that hit the church. If we did it now, we wouldn't be able to write some lighthearted sitcom because I find the child abuse stuff so depressing.

Do you ever suffer from Catholic guilt?

No. I was the first generation who really didn't give a damn. As soon as I hit puberty, it was over.

Father Ted launched the career of Graham Norton. Do you still keep in touch?

We don't really keep in touch but it's always great to see him. I saw him walking his dogs recently and we had a nice chat.

In 2009, you started a "We love the NHS" campaign on Twitter to counter claims being made in the USA about the NHS...

The right wing in America is such a poisonous source of propaganda that when they started using the NHS to argue against Obamacare I thought the best way of fighting back was the same kind of propaganda – and it worked – but it limited the usefulness of the conversation. I tried to do a later hashtag for "NHS problems" but it died a death because people didn't want to admit there were any problems. It's hard to predict what will be effective. Another example of how it failed was that both Gordon Brown and David Cameron said it in their speeches: a little pause, then: "We love the NHS." You could not get more meaningless than David Cameron saying that.

Do you have a low opinion of our MPs?

One thing that's happening that I find fascinating is the porn conversation. It's a perfect example of people wanting to appear to be doing something… [and] of the Tories trying to outsource government responsibility to private companies in a way that could limit our freedoms and restrict the net. The net is a very precious thing. I hate it when people discuss measures to limit it.

You've reimagined Count Arthur Strong [the award-winning Radio 4 show] as a TV series for BBC2. You seem to be making a habit of translating things from one medium to another.

That's my modus operandi now. Next I'm going to take a poem and turn it into a car.

The Ladykillers is at the Vaudeville, London WC2, until 26 Oct. Count Arthur Strong starts on BBC2 on 8 July