POPULAR EX CATHEDRA CONDUCTOR TURNS 70 JEFFREY SKIDMORE'S 70TH BIRTHDAY by Christopher Morley Like Oscar Wilde's Dorian Gray, Jeffrey Skidmore probably has in his attic a picture of himself which does all the ageing for him. See him downstairs and you would never believe this conductor of Ex Cathedra is about to turn 70. For all the worldwide success he has achieved with this chamber choir which was his brainchild Jeffrey remains remarkably modest and down to earth, with absolutely no "side" to him. Our Birmingham-based careers in music have developed side-by-side for over 50 years, and he tells me how his began, thanks to an inspirational teacher. "I went to Bournville School in Griffins Brook Lane, and the music teacher was Walter Jennings (who now lives with his wife Linda in Plas Gwyn, Elgar's old home in Hereford). "They were both music graduates of the University of Birmingham, and introduced me to the music scene in the city, in