LOOKING for clues to the real Sherlock Holmes is difficult because there's someone else in the way ahead of you, bending the grass and throwing shadows on the trail.It's actor Jeremy Brett, who's still in hot pursuit of Holmes himself, even though this is his seventh year pursuing the enigma-in-top-hat as the star of PBS's "Sherlock Holmes" series, which tonight begins its first of five new episodes on "Mystery." I am sitting waiting for English tea for two and Mr. Brett, who plays a tall, brittle, sniffish Holmes in Victorian mourning, when a guy in a large, hunter green sweater and white linen trousers ambles up. He flashes a smile, a handshake, and sits down for the Holmes interview. Even the fiendish Dr. Moriarity, Holmes's nemesis, would not see through this clever disguise. The covert face looks altered from Holmes' TV face, which is narrow, pensive, slightly pinched with disdain for those less observant th an he. The only trace of Holmes is the hawklike nose, still bold in a now relaxed, open face. Whereas Holmes looks long, thin, and furled as an umbrella, Brett radiates expansiveness, bonhommie. He is built like a fullback, with a slight tan, wide green eyes and ash brown hair. He is a contrast to the pallor and black hair, black clothes of the slightly sepulchral Holmes. He begins by telling me that it's been a little bit like after-the-fox playing the great detective. And he speaks of Holmes as though he's present: "He's as tough to play as Oedipus or Hamlet or Macbeth. Why he fascinates me still is the fact that I still can't play him, he's still one field ahead of me. He pauses. "Two fields. It's like a treasure hunt." Is Holmes then the mystery still eluding Brett as an actor? He turns abruptly on me, with the slightly scornful expression that daunts Inspector Lestrade's every question. "Well of course," says Brett, "He's better read. The truth is, Doyle's creation is better read. To try and bring flesh and blood and visualization to Doyle's brilliant creation is almost beyond any one person's comprehension." Although a fan of Holmes on TV would recognize him from just a few of his mannerisms like the falcon look he gives a clue before springing on it, Brett discounts that. "Mannerisms ... I didn't mean to [do]. You see, the trouble is my image of him.... I see him as a kind of marble statue. I mean I try to see a vein in the marble, that I can act in. But he's described by Arthur Conan Doyle through Watson's mouth as 'a mind without a heart.' But if you're an actor, the first thing you do is go to the heart of the matter." He laughs. Over 100 actors have tackled the Sherlock Holmes role in the last century, including John Barrymore, Richard Burton, James Mason and perhaps most famous up till now, Basil Rathbone. Many critics cite Brett as the most convincing Holmes of all, and Doyle's daughter, Dame Jean Conan Doyle, told him that he "was the Sherlock Holmes of her childhood." Brett says, "The great Basil Rathbone is of course my Sherlock Holmes because he was the first one I saw.... the rest were derivatives. But he's always going to be my Sherlock Holmes. "Oh, I think there are many actors probably who just popped on the cliches: the Inverness cape which he never wore, the calabash pipe he never puffed, and they just walked through their lines on their way to their next part." Brett plans to do the "the entire canon" of Doyle's Sherlock Holmes stories for Granada Studios with this season's "The Casebook of Sherlock Holmes." He's already shot 34 of them. Brett intends to go on to do the last 22, a record no one else has ever attained. His favorite of this year's "Casebook" series is "The Problem of Thor Bridge," about an American gold-mine millionaire (Daniel Massey). Brett says, "It's got the best piece of deduction in probably all the stories." Brett has also played Holmes fo r Granada in a new two-hour special, "Charles Augustus Milverton," in which Holmes gets his first kiss at 37. What about Holmes and women? He runs his hands through the mop of hair which falls over his forehead and twinkles: ve made up this little story that probably when he was at university, he saw a girl across the quadrangle, lost his heart; she didn't look at him, so he closed the door." Brett, unlike his alter ego, has been married twice and has a son, David, a painter, by his first marriage to actress Anna Massey; and a daughter Rebecca as well as a stepson Caleb by his second marriage to the late Joan Wilson, a producer for WGBH. "She sustained 'Masterpiece Theater' for 17 years and created 'Mystery.' She was a milkmaid from Wisconsin, really, originally, and a quarter Cherokee, a breathtakingly beautiful woman," whom he still mourns. Brett confesses to having been born in Yorkshire with a silver spoon in his mouth, being educated at Eton until he dropped out because of an illness. After that he ran off and studied at a drama school. There was never a question about what he wanted to do after he first saw Laurence Olivier on stage and dreamed of working with him. Brett was directed by Olivier in some of the great Shakespearean roles at the National Theatre. "He said this amazing thing once, 'I expect every young actor who works with me to have the body of a god and the vocal range of a full orchestra.' And he had both." Brett mentions, "I think I'll go offer my services to [today's Olivier] Kenneth Branagh. I'll join the younger generation." Then the man who has played Dracula and Troilus and Alex de Winter in "Rebecca" and dozens of other roles popped off to the National Press Club to say a few more words about Sherlock Holmes. The following night he gave a brief, poetic speech at the British Embassy, where a reception had been given in his honor. He turned up looking exceedly dapper, handsome, and contemporary in a dark blue suit. But as he swung briskly away from the podium and out of the room, the face was again that of the ultimate myst ery, Sherlock Holmes.