Diana Rigg once famously described Bertolt Brecht's Mother Courage as "a female Lear with songs" and, like Lear, it is a role that attracts performers of a certain age and a definite star quality. Other great names associated with it are Judi Dench, Glenda Jackson and now Kathryn Hunter. But then, if you are a star actress and want to tackle a demanding role, you may as well choose a play by Bertolt Brecht. The inventor of "epic theatre" was the first modern playwright to give women big leading roles, many written for his wife, Helene Weigel. And Mother Courage is certainly a big role - the actress playing her is offstage for only one of the 12 scenes, and she must pull a cart around for much of her time on it. And she has to sing.
Brecht wrote Mother Courage and Her Children in 1939 while living in exile in Denmark after fleeing Nazi Germany. It follows the travails of Mother Courage, who sells her wares from her famous cart to soldiers and camp followers during the Thirty Years' War - the conflict that devastated central Europe during the first half of the 17th century - and who changes sides (from Protestant to Catholic) at least twice. It is an allegory of the horrors of modern war, and makes clear the complicity of many characters who are caught up in it. Mother Courage is in no way an innocent onlooker - on the contrary, she makes a living from the conflict. Yet by the end of the drama that she is transformed into a victim of the war, having lost her three beloved children to it in various ways.
It is easy to see why Mother Courage is such a tough part. How do you make an audience empathise with this appalling woman without making it sentimental? The only one of the list to have tackled both King Lear and Mother Courage is Hunter, who did an acclaimed Lear in 1997 and is about to star in Lee Hall's version of Mother Courage in Oxford. Is she a glutton for punishment? "It's another very big role, yes, but the good thing about Lear is that it didn't have many props," says Hunter, despairing at all the stage business that must be done with Mother Courage's cart and its contents. "But Brecht, much like Shakespeare, does ask you to find the tragedy and high farce and to be able to move very deftly between the two."
Does she agree with Rigg's Lear parallel? "There's not the journey towards madness that happens in Lear, but at the end when she has lost her three children, something snaps. There's certainly that huge emotion, but the hardest task is serving Brecht. He doesn't want her presented as a heroine, yet what he has written calls for empathy.
"There is this constant pull between her wanting to be the best mother in the world and get her three children through the war unscathed, but also wanting to be the best businesswoman in the world and make as much money from it as possible. The two strategies are incompatible and that clash has to be operating all the time."
Why has she taken it on? "I like the challenge and it is a mountain to be climbed." Is it an Everest for actresses, then - it's there, so they have to climb it? "Yes, perhaps," says Hunter. "I had always had a fantasy about playing it, and when [director Nancy Meckler] proposed it I was delighted. But the basic reason for doing it is that Brecht is the most extraordinary dramatist."
While Rigg and Hunter can see the Lear parallel, Glenda Jackson doesn't entirely agree. The actress- turned MP made the role her swan song from the stage before she entered politics, performing it at the Glasgow Citizens in 1990. "It's a huge role - you're in practically every bloody scene - but I'm not quite sure it has the range of Lear. Although I suppose the great emotions, in that she is passionate about her children and suffers great loss, might suggest that. The challenge for the actor, though, is trying to not make her heroic. That was not Brecht's idea at all."
Although all the actresses agree that the role should be within the range of a talented young actress, Rigg believes that it's one, like Lear, that only middle age can fully illuminate. "Mother Courage's age is never stated, but she has three grown children, so she must be at least 40. She has clearly lived a long time," says Rigg. "I did it in my mid-50s and it's that 'encrustation' that comes with living a few years that informs the part."
When Rigg played Mother Courage at the National in 1995, part of the attraction was the chance to overturn standard perceptions of her. "I have this image as a rather grand leading lady, and I came on stage as a working-class woman with broad Yorkshire vowels. David Hare [who did the adaptation] knew I come from Yorkshire, so he decided to use that."
Rigg's performance was described as Bet Lynch-meets-Marxist dialectic and she clearly had fun in what is regarded as A Very Serious Play. "The humour is there; it just needs to be brought out. I must say it was a joy to do, but bloody hard work - pulling that blessed cart around for three hours every night."
Judi Dench played the role with the Royal Shakespeare Company in 1984. She wasn't aware of these details when she took the part, which she accepted without even reading the script - as is her practice - relying on Brecht's reputation for writing great roles for women. "When the director, Howard Davies, told me the story of Mother Courage, he didn't tell me she was on stage so much and he didn't tell me I had to pull round this enormous cart. So on the first day of rehearsal I thought, 'Fuck this. I never have a scene off.' I was so angry. But it was my own stupid fault, of course."
While Rigg enjoyed playing with her image, Jackson was just grateful for a part to get her teeth into. "God knows, there are few enough roles for women anyway, but ones this good are exceedingly rare. And this is a great role in a great play. It's a popular myth that there are great roles in lousy play - there aren't, quite simply. I feel privileged to have played her."
Hunter, meanwhile, is still getting to grips with the role, but is heartened when I say I have an interesting anecdote to pass on from the MP. "Helene Weigel said she based her characterisation of Mother Courage on Broadway singer Ethel Merman - it was that big, blousy aspect that attracted her. I personally found that an illuminating way to get into the role."
"Ah," says Hunter. "That's fascinating. I wonder what she meant. But I've still got a mountain to climb."
Mother Courage and Her Children is at Oxford Playhouse (01865 798600) from today, then at Brighton, Leeds and Sheffield before opening at New Ambassadors, London WC2 (0171-836 6111), on April 25.
