Can I be the first female to ask the obvious one: will you marry me? Susan Bradley, Iowa

No, I won't. It's very kind of you to ask, but I make it a rule never to marry people I haven't met. I don't mean that in any way to cast aspersions on various customs in other religions. I think that's an absolutely bang-on way to go about arranging society.

What is it that you most love about Britain? Katherine Curran, Dublin

I think the thing I'm most fond of is our self-criticism. Whenever people say: "We don't like winners in this country…" I think: that's great – it puts life in balance. They've got their winnings; why do they have to have the adulation as well? In America you have the relentlessness of a culture that believes so strongly in its own meritocracy that if you're a failure not only do you have to live with all the trappings of that failure, you have to live with the thought that you deserve it. At least when we see someone's success we've got the inner bitterness and cynicism to assume they've got it through luck or dishonesty, not merit.

What does Stephen Fry smell like? Liam Sean McKnight, Edinburgh

I don't know; I haven't got close enough. I've shaken his hand but I've never smelled his neck.

You've been pretty successful – are you surprised you haven't been taken down by the naysayers? Ben Horton, south London

Now there's the internet, everyone has been shot down in flames. I'm not too proud to self-Google every so often, and I don't always like what I read. I read in the Mail that Peter Hitchens had referred to me as a "so-called comedian". That particularly annoyed me, because it doesn't work. He can disagree with whether I'm funny. But I just am a comedian! You might as well say "so-called dentist".

As someone who's been quite anti-football, are you pleased England didn't win their World Cup bid? Gareth Jones, Liverpool

Not in a way I'm proud of, but there's a glimmer of schadenfreude. My problem with football is the feeling that there's such a consensus about its being interesting. When England is playing in a tournament, there's such huge pressure to give a shit that I perversely end up giving less of a shit than I would without that pressure. And the way advertisers get involved sickens me – there was a big neon banner on the BT Tower the day of the bid result saying something like: "BT supports the England bid". It's meaningless – it's just a faceless corporation trying to buddy up to us to take more of our money. But I try not to be pleased that the bid failed, as having the tournament here would have given a lot of football fans a lot of innocent pleasure.

From what point in your career did you begin consciously creating a comedic or public persona that was, at least in part, different from your actual self? Helen Young, Welshpool

Ah, I think I was six. [Laughs] I don't know whether I have consciously created a persona. When you're on a panel show, for instance, you very naturally caricature yourself. For me it's come out of the desire to get a laugh – and the desire not to tell people everything about myself.

Who was funnier when you were growing up, your mum or your dad? Mary Elizabeth, Illinois

My dad. He's always been into comedy, although neither of my parents had any yen to perform. They were hotel managers, but when I was two they gave it up because it's not a very family-friendly job, and taught hotel and restaurant management in what is now Oxford Brookes university.

Your bits on Bruiser [a BBC sketch show Mitchell and Robert Webb worked on in 2000] were funny. Could you recycle them for your sketch show? No one would know… Bob Debris, Bath

Few people would know. Yes, we learned the hard way that it's quite possible for something to be both on BBC2 and barely noticed. But it was the first proper television we did, and it was very exciting – we were part of this little gang of sketch comedians, including Ricky Gervais, who wrote three or four sketches for it before he made his name, and we rather thought we might shoot to stardom as a result. Obviously we didn't.

If Mark and Jez were adrift in the open ocean, with little chance of a timely rescue, who gets eaten? Robin Lindsay, Halifax, Nova Scotia

Do you mean which of them would eat the other? I don't think a shark would particularly go for one ahead of the other – "Oh, Jez, he's so easy going; he'll be less sinewy." [Pause] I think Mark would eat Jeremy. I don't think it would happen quickly, but basically Mark has a colder, more evil heart. Jeremy's flaws are all in weakness, whereas some of Mark's are in conviction.

What kind of process do you and Robert Webb use when you are writing a sketch for your television show? Do you have a method or is it just comedic chaos? Stephen Clarke, Nanjing

The ideas come out of group meetings with other writers, or pub sessions. You never sit down at a computer unless you know what sketch you're going to write, because that's when the blank page is terrifying. That's the extent of the method.

How did it come about that you got a 2.2 at Cambridge? You seem to have that rare capacity to think authentically for yourself and stick to it. Did you have the feeling that capacity wasn't honoured at Cambridge or were you simply a lazy arse academically? Cathy Earnshaw, Berlin

David Mitchell and Robert Webb as undergraduates at Cambridge. Photograph: David Mitchell

I was a lazy arse. I got a 2:2 and I was grateful for it. I only spent three weeks working, and it would be a pretty poor university if I'd got anything better with the effort I'd put in. Getting up very late, getting drunk a lot – I'd love to say I just didn't have the hours to do history, but what I didn't have was the ability to focus on it. In my first term at Cambridge I was in this exciting group of people who were all saying they wanted to be professional comedians and actors and so I said that, too.

You're a big cricket fan – are you staying up to watch the Ashes? Christine Alexander, Tring

No, only occasionally for the first session. Much as I like cricket, I'm a bit of a fair-weather fan – literally, it feels more appropriate to the summer. This time of year is for mince pies and, to me, that doesn't go with a sun-drenched Test match. I have no plans to emigrate to Australia.

If you could meet any comedian, living or dead, who would you like to meet? Leslie Cummins, Camden

Peter Cook. With most comedians the thing that's best about them is their work, not what they're like to meet. There's no comic actor I admire more than Peter Sellers, for example, but from the stories I hear I'm better off not having met him. But Peter Cook struck me as not only a very funny person who did some brilliant work, but he just seemed such fun. I doubt I could have kept up with him for long, but maybe for the first half of the evening…

This is a rhetorical question, David. Do you realise that by not having lots of casual sex with groupies you are criminally wasting the greatest privilege of appearing on mainstream TV? Chris Morris, Manchester

Now tell me: a rhetorical question, that's a question that doesn't require an answer, right? [Silence]. Noted. Piece of rhetoric noted.

Are you still single? And if so, is it because you're picky or fiercely independent? Anne Thomas, Llandudno

Erm… um… er… At the moment I've sort of recently started seeing someone. I'm not fiercely independent. I don't know – a bit picky, maybe? But also maybe other people are picky!

Mark's just had a baby boy in Peep Show – do you fancy parenthood yourself one day? Kate Macauley, Luton

I can't see myself as a parent – it terrifies me, but I'm not saying never. I've not really answered that question to my own satisfaction, let alone anyone else's.

Do you feel self-conscious about walking down the street? Jonathan Hill, London

"I'm less self-conscious about my self-consciousness now". Photograph: Phil Fisk for the Observer

I feel more self-conscious than I did, yes. But I'm less self-conscious about my self-consciousness now.

Do you still walk for an hour each day? Michelle Murtagh, Dublin

Yes, I do. I had a bad back a few years ago and the walking sorted it out. My rule is it has to be brisk: I've always been a fast walker. And the reason for that is that I'm always late.

Jaffa Cake or biscuit? Robert Nelson, Bath

It depends on the biscuit. I'd prefer, for example, a plain chocolate digestive, or one of those Boasters, the ridiculously expensive ones where a packet costs about £9.95 and you get three of them. In liking those biscuits I feel like I've been emotionally engaged by a West End musical: I'm a bit too susceptible to something cheesy. Metaphorically cheesy. They don't taste of cheese at all.

Do you ever get a bit sick of… [Interrupting] See how much happier I am to answer that question than, say, Gordon Brown. Where's he now? I think at that Mumsnet interview he should have just said: "I'm the fucking Prime Minister! What a trivial fucking question, why don't you go fuck yourself?" I would have voted for that man forever if he'd said that. I would have moved to his constituency always to be able to vote for him.

It's perfectly reasonable to ask comedians questions about biscuits, by the way.

Do you ever get a bit sick of Robert Webb?

Joe Holyoake, Shrewsbury

David Mitchell on stage with The Two Faces of Mitchell and Webb. Photograph: Geraint Lewis

Oh God yes. But at the same time I think he's brilliantly talented and he's one of my oldest friends. We've had to spend a lot more time together than friends usually do, and we're not in love. So we both get sick of each other and we have to be careful in giving each other a bit of space. But I don't think there would ever be a point where we'd say we're stopping working as a double act now.

I imagine Matt King is as impulsive, wild and charismatic in real life as his on-screen persona, Super Hans. Is this an accurate observation? He seems like the kind of guy you want at your party. No offence – I'm sure you'd be a riot, too. Dick Smith, Sydney

None taken. Matt King is certainly charismatic, but I'd say he is not as impulsive or wild as his on-screen persona– and good job, too, for his wife and child. He's a sensible, successful man, not a crack-addled maniac.

Where would you be now if Peep Show hadn't come along? Saffron Clague, London

Mmm, I don't know. Peep Show's been the biggest boost to my career of anything I've done. I had written on lots of things before and Rob and I had our own radio show commissioned at that point, so that would still have happened, but whether it would have gone on to be a TV show I don't know. I hope I'd be a working comedian, but I don't think I'd be as well known or successful as I am.

Where did you imagine you'd be at this age when you were a child? Anna Fruen, Cardiff

I once wanted to be prime minister. But doesn't everyone? It was no more serious than the time a couple of years earlier when I wanted to be a wizard…

Since the Lib Dem/Tory coalition has turned out to be a little less exciting and progressive than promised, it's clear that we need some fresh blood in the system. If you could start your own political party, what would it be called, and what would your policies be? Emma Worgan, Bournemouth

[Looks worried] I can start my own political party – we live in a democracy and everyone can! I hope people do know that, don't they? So the answer is: if I could start my own political party, which I can, I wouldn't, so I haven't. But if I did it might be called the Whigs. I always think it's a shame that that name didn't stick around. And their policies would be centre-left, bit of redistributive taxation but let's not go mad. And as I got older, they'd be more and more right-wing…

What's your view on WikiLeaks? Jaana Tyni, Finland

I think the actual revelations themselves are surprisingly unsurprising. It's what we would all have imagined that American diplomats were saying confidentially to each other. The question of whether or not they should have been leaked, I don't know. Obviously the diplomatic service needs to keep secrets, but it's up to them to keep them, not other people.

When was the last time you cried? Abigail Graham, London

I haven't cried since about 1996. Occasionally I get a bit of a sense of a prickle in the eyeballs, but I can't stop myself suppressing it, which I hope isn't going to store up all sorts of psychological shitstorms for later.

When are you happiest? Linda Peters, UK

When something I've been stressed about getting done has finally got done. That's a glum but accurate answer, I think.

You seem to be involved in a lot of projects. Is this because you're afraid of work drying up at some point? Lise Qvottrup Larsen, Aarhus

To a certain extent. Also, the stuff I'm doing, I like it and I can't necessarily assume an equivalent offer will exist in a few years' time. But I'm not a workaholic. I'm lazy, basically. There are times in the past when I have been tremendously indolent, and I look forward to them in the future.

Are there enough panel shows? Ben Williams, Oswestry

Probably, to be honest. But there are enough people, and yet there are people having sex...

Can you see yourself wanting to remain a TV personality? Roisin Kennedy, Dublin

There's no other job I'd like to do. I'd like to carry on writing alongside it, but no, this is the job I've always wanted. I'm not a "new challenges" kind of guy.

As two men who are getting on a bit, my flatmate and I can't help identifying with the Peep Show characters. But which of us is Mark Corrigan? We both share a passion for military history and regularly compete with each other on high-brow quiz shows. But while one of us flies model helicopters, the other has read all the historical novels of Patrick O'Brien. Please advise, as neither of us wants to be Jez. Tim Snelling and Paul Radford, Ventnor

I'm afraid you're both Mark Corrigans. Unless you're Mark Corrigan and Alan Johnson. I will say this: the historical novels of Patrick O'Brien are excellent.

Peep Show and Tell is on Christmas Eve at 9pm on C4