BRENDA Blethyn is far from sure that she has done the right thing. Before she embarked on the publicity tour to promote

Little Voice, director Mark

Herman's follow up to Brassed Off, she was laid up with the

flu. In her confused state, she now worries, she turned down Ken Branagh.

The one-man celluloid Shakespeare machine wanted her to appear in his latest screen adaptation, Love's Labour's Lost. Blethyn said no. There are other projects in the offing that are dear to her heart. And . . .

''I'm a bit nervous of Shakespeare,'' she admits. ''I did a few at the National Theatre. I was in Bill Bryden's Dream, and I was Cordelia in King Lear for the BBC. After that I met a TV

critic on Westminster Bridge who told me my interpretation was wonderful but technically I had some way to go.''

Either he was a know-nothing or Blethyn has been travelling swiftly and purposefully since. Technically, Brenda Blethyn is one of the most accomplished screen actors we have.

Since she was recognised with an Oscar nomination and a Golden Globe for her performance in Mike Leigh's Secrets and Lies, she has made a further six films, none of them either very obvious or very visible. For Blethyn, however, they have

all been interesting and that's what matters.

Little Voice, although it has had mixed reviews, has the look of a movie that spawns further awards. Jim Cartwright wrote the part for Jane Horrocks, who claims (disingenuously, one suspects) to have been shy about having her talent for mimicry of the classic songstresses brought to the front of the stage. She has been less reticent, however, about expressing her views on Hollywood's suggestion that her part be given to Gwyneth Paltrow, and Blethyn's (LV's Mum) to Meryl Streep.

In this alternative cast, the Ewan MacGregor part (the only member of the company to follow the director from Brassed Off) is played by Brad Pitt, whose mother Blethyn played in A River Runs Through It. One suspects that the whole scenario is hype, but Blethyn is less willing to dismiss it.

''It would still have been a good film, but very different. Yes, Jane's part was written for her, but Mark has broadened the piece out. Ewan's is a much bigger part. And the cabaret scene, which is the climax on stage, only has its full impact on screen, because in theatre it has to be played in front of the tabs.''

Blethyn's screen presence has arrived in the third decade of her career. A job as an office worker and a failed marriage (to Mr Blethyn) behind her, at 27 she followed her interest in amateur dramatics to drama school in Guildford, where she is now on the board of governors.

She talks of the characters she has played on the large and small screens as friends (''Cynthia, in Secrets and Lies, was a loser in every department. Her generosity was her downfall''). They are personalities she has constructed in pursuit of her craft. Small wonder she was suited to Mike Leigh's meticulous working methods.

''The only real difference in what I do has been in the Mike Leigh film because of the way you arrive at it. You have to do your research. You have to find out how your character arrived at page one. With Mike Leigh you all invent that together.''

As others have observed, Brenda Blethyn is altogether lovelier in the flesh than she has ever appeared on screen, but, at 52, she is not simply realistic about the parts she is offered, but relishes the opportunities.

SHE says: ''I don't get offered glamorous parts. I'm asked to play ordinary women so there are a greater variety of roles. In fact, people have the same problems. Instead of worrying about who to leave the Rolls-Royce to, it's the Ford Anglia.''

It's an attitude that chimes well with a life-long Labour supporter who, refreshingly, takes no particular interest in individual policies because ''that's not her job''. When those policies impinge on her craft, however, she can be as outspoken as Marie Hoff in Little Voice.

''I had to have a grant to go to drama school, but the situation now is desperate for young people starting out. It is a terrible state of affairs.''

Blethyn does what she can by making a donation from her screen earnings to her old school to help subsidise places, but prefers the system in Australia where a further education grant is automatic and paid for by future taxation. That knowledge comes from time spent there filming The Winter Dark with former Troubleshooter Ray Barrett.

She's hoping to return there next year to make a biopic about pioneering photographer Julia Margaret Cameron with John Hurt as Alfred Lord Tennyson.

There is a lot of interest in Cameron at present (she is currently the subject of an important exhibition at the Art Institute of Chicago, of which more in Monday's Herald Arts) and it is one of those projects that is dear to Blethyn's heart. The Bard and Branagh will just have to wait.

n Little Voice is on general release.