THE interesting question at the BBC is whether John Birt, director-general designate, will appoint a deputy. The view of the wags is that after his experiences in that job, this would be unwise. Meanwhile, Sir Michael Checkland, the present director-general, appears surprisingly cheery. It may be that, by sticking to his contract, which runs to February 1993, he has achieved something useful: he has exposed the inadequacies of the board of governors system, and of the style of the board's chairman, Marmaduke Hussey. A growing view is that the BBC needs a pragmatic businessman - on the model of the ITC's Sir George Russell - as deputy chairman, to replace Lord Joel Barnett next year.