The Falstaff of Merry Wives of Windsor is very different to the Falstaff of Henry IV Parts I and II. In Merry Wives he is, pardon the pun, a lightweight version of himself. And lacks all the layers of characterisation that he has in the Henries, as we call them. Having played him in the Henries, I think I would find it a less satisfying experience to play him in Merry Wives.

I, like many other actors who have joined the RSC, used to believe that there is a prescribed way of playing Shakespeare. There isn't. Each generation devises their own way dependent on how audiences want to receive Shakespeare. Earlier generations of audiences were happy to hear him almost sung or performed in a very grand operatic manner. Modern audiences want him to be done more realistically, they want to recognise the characters on stage as people they know in their lives.

So it will keep changing, but there are some basic rules about playing Shakespeare that it is best for actors to know about even if they then choose to discard them. Playing Shakespeare in a totally naturalistic way with the mumbling of modern speech, the tendency to fall away towards the end of a sentence, this simply wouldn't work when speaking Shakespeare verse.

I was very lucky to join the RSC in the early 80s at a time when the company existed almost like a training school as well as a performing ensemble. And we had workshops and one-to-ones with some truly great Shakespearians, like John Barton and the great voice guru Ciss Berry. It often struck me that it was incredible that we were being paid to learn about Shakespeare from these people, it felt like it should have been the other way round! But Greg is very much carrying on that tradition. He's a great disciple of John Barton - he's absorbed and learned a lot of his principles about speaking and performing Shakespeare. And they meet up regularly to discuss things, and I think of them as the spirit of RSC past and present in wise consultation with one another.

I talked earlier about the theme of persecuted people turning into persecutors - Richard is a fine example of this. In his famous opening speech, which begins "Now is the winter of our discontent", he describes very graphically what it is like for him as a disabled man to be in society. It has clearly damaged him considerably. I think there's a lot of evidence of self-hatred in him. But it also fuels a very special energy that he possesses, which is a destructive energy, in that he goes on to destroy the lives of quite a few people around him.

But in typical Shakespeare fashion, he is written with such wit and black humour that an audience ends up relishing his machinations. It's one of the fascinating things about Shakespeare: how he makes an audience enjoy characters whom if they met in real life they'd run a mile from. I just enjoyed playing the complexity of a man whom nature has given a rough deal, and yet who ends up being such a huge force in the story.

It tends always to be the one you're playing at the moment. But in this case, it could end up being an all-time favourite. Partly because Falstaff is not a part I'd ever dreamed of playing - look at me! He's so far away from me, in every aspect, that when Greg did suggest it, I just couldn't picture myself doing it. And spent quite a long time with him trying to persuade me, and me trying to work out whether I could do it. Every actor who plays Falstaff has to wear a fat suit, but it isn't just his physical aspect - his personality is enormous, everything about him is different to me.

Eventually that became the hook for me. Like what I was saying about how I love character acting - here was going to be a feast of character acting, bigger and better than anything I had tried before. Now that I have done it, and it seems to have worked out quite well, I just keep thinking about how much poorer my life would have been had I not done it. It's been a really special experience.

I think Macbeth is possibly Shakespeare's perfect play, it's a perfect play in the writing. It's very hard to do, and defeats most productions, because the themes of the supernatural, murder... they're very hard to make real and put on stage and be as frightening as they are when you just read it. But in the 1999 production that Greg directed, and I played Macbeth with Harriet Walter as Lady Macbeth, we did succeed in making it work. That was something we all felt very proud about. We went on to film the production for Channel 4, it exists as a DVD if anyone wants to look at it and agree with what I'm saying!

I agree that the teaching of Shakespeare in schools is very important. I was not taught it well at my school, and it almost put me off it for life. I suspect this is quite a common experience. I wish that kids could be brought to see plays performed at Stratford, before they even read them - he was after all written to be performed, rather than read. But I think a very hopeful thing is happening at the moment, that our Live From Stratford broadcasts, which go out to cinemas round the country and round the world, are then streamed live into schools, and we've had some terrific responses of teachers saying that it's really engaged the kids in a way that other more conventional ways of teaching haven't always achieved.

The iambic pentameter side of it is secondary to his powers of characterisation and storytelling. If kids get bogged down in trying to understand what iambic pentameter is, they'll miss out on the really exciting stuff in Shakespeare. The great stories, the things they can identify with. That's at the heart of Shakespeare, not the way he writes verse.

I think Meryl Streep is the greatest actor in the world. I'm very passionate about character acting, and her powers of character acting are phenomenal. Her powers of transformation, whether its becoming a British prime minister or a Polish survivor of the Holocaust, or a Danish farmer in Out of Africa, they're just phenomenal transformations.

But what she does that makes her really, really good, is put her own heart and soul into these characters so that it isn't just a technical exercise of changing her accent. There is a living, breathing person there, that you care about. That combination of transforming herself through acting, and yet playing with her own heart and soul, is a great gift, and I would just love to have some close up view of her working. I'd be prepared to play a doorman opening the door for her, if I could just have a couple of days on set with her, watching her work. She does theatre work I suppose... we could do a play together, in my dreams.

I've had very good training for this particular hurdle, in that every time you come to play one of the great Shakespeare roles, you're following in very famous footsteps. If you thought about that too much, you'd become paralysed, and wouldn't be able to play it at all. You just have to get over it! And get on with the job.

That early experience of Richard III, I was up against it there, Olivier had done a very famous interpretation, and the bastard even went and filmed it. People around the world can do interpretations of his Richard. That was a very good baptism of fire: "stand aside Larry, just give me a little bit of space to do my own version!"

Luckily I haven't seen Death of a Salesman on stage, ever. I've seen a couple of the filmed versions and they're not quite as powerful as I think the experience will be on stage. The play is more of a dream than film versions do, because everything becomes a bit literal on film. In Arthur Miller's writing, you go right into Willy's head as he's falling apart. It's very painful, very poignant, I think.

It's very rare that film scripts are as good as theatre scripts, so I just haven't really been that lucky to get many of those really well written films come my way.

Yes, absolutely, I'm putting the finishing touches to one of my theatre journal books. The first of these was called Year of the King, about playing Richard III; this one is called Year of the Fat Knight, about playing Falstaff. And like that earlier book, it's diary entries over the year of preparing and rehearsing it, interspersed with my drawings and sketches of other members of the cast, various famous actors who have played Falstaff over the years, etc. That's being published in June next year.

Both. And Falstaff's a really good example. I don't think there's any other character in Shakespeare that's described as physically as much as Falstaff is, in terms of his size and weight. The actor who's going to play him, together with the designer and director is going to have to conceive of how to play that physical shape. That's from the outside in. But on the other hand there is also a wonderfully complex, rich character that Shakespeare has written, that you've also got to investigate and play, and certainly that's from the inside out.

Falstaff is a totally selfish man, completely egotistical. He has a line at one point about "this little kingdom man"; he is a kingdom called Falstaff. He can be the life and soul of the party, is enormously witty and subversive and exciting to be with. Which is why the prince has become best buddies with him. There's a terrific contradiction - he lives just for himself, but you don't half have a fun time with him, if you spend an evening in the Bull's Head tavern.

I'm really proud of doing that film. I fear that the HIV/Aids theme meant that it wasn't perhaps seen as much as it should have been. I did as part of my research consult with social workers, and they gave me very valuable material in creating my character.

It's always so important what the quality of writing is like, and Martin Sherman, the way he had written my character who is a social worker working with people with HIV and Aids, and who then falls in love with one of these people, it was a brilliant piece of characterisation. Because he shows how the pressure on my character leads him to drink too much, to be flawed in many ways, although he's doing such good work. I love that ambiguity and contradiction in characters.

When Greg got the job, we both took a deep breath and said right, well, we've got to find a way of making this work. Because there are many stories of the artistic directors at these big companies having nervous breakdowns, or their marriages falling apart. It is a superhuman job. So far, touch wood, we've incorporated it into our lives and a really important thing is we make sure to take regular holidays together, to actually carve out times together. That has really been an important part of the equation.

We've worked together so many times over the years as director and actor - 10 or 12 times. That hasn't altered with his new job.

There's a strange inverted snobbery about the RSC. I just discovered that if I was to have my career as a theatre actor, rather than in movies and TV, there was simply nowhere better to be than the RSC and to devote my career to playing Shakespeare. I can't picture a more satisfying career than the one I've been lucky enough to have.

We take Shakespeare too much for granted in this country, we can almost forget what a genius he is, how brilliant he is. When you play one of the great parts and if you succeed in finding a way to play it, it's more satisfying than any other acting. It's his remarkable insight into what it is like to be human, his characters together become an astonishingly comprehensive picture of us all. He deals with every single aspect of all of us - there's no other playwright that's ever done that, will ever do that.

I believe 100% that the actor from Stratford, William Shakespeare, wrote the plays by William Shakespeare, and I've never seen a shred of evidence in any of the conspiracy theories to make me believe otherwise.

I think Peter Flannery's Singer is one of the best modern plays. It was a tremendous experience being in it. It was revived at the Tricycle about ten years ago but I'd like to see it go into the repertoire of modern classics and be performed regularly.

The theme of the play is one which has preoccupied me a lot in my writing as well as acting of the persecuted turning into the persecutor, and with Singer we see a man who was in a concentration camp, and suffered there, and turns into this ruthless Notting Hill landlord based on the real life character Rachman, and then eventually being redeemed.

Classics are just always contemporary - you just apply them to whatever is happening. That's why Shakespeare can be done again and again.