P219 ORACLE 219 Fri31 Dec ITN 0030:00   MacGREGOR'S GRIM  WARNING TO STEELMEN British Steel boss Ian MacGregor has issued a grim warning to workers of further cuts in the industry. In a letter to employees he implores workers to "buckle down" in a year in which "the luxury" of a central pay award cannot be affordedN "Only a lean, hard and efficient British Steel can survive the present famine," he says. Steel union leader Bill Sirs reacted angrily to the letter, accusing Mr MacGregor of "brainwashing" his members