To quote from the Varsity Pilot's Notes:
Oops pressed the wrong button! ' After take off, to commence climbing, reduce r.p.m. to 2400 and set the throttles at the R.B. gate (+9 lb/sq.in). As height is increased above about 3,000ft I.S.A., the indicated boost will fall. When the boost has fallen to +7 lb/sq.in (at approximately 5,250 feet I.S.A.), 'S' should be selected if the climb is to be continued. Before selecting 'S' the boost should be reduced to 0 lb/sq.in. After selecting 'S' gear, open the throttles to the R.B. gate, when the boost should be restored to +9 lb/sq.in. The full throttle height using +9 lb/sq.in and 2400 r.p.m in 'S' gear is approximately 11,000 feet I.S.A., after which it falls steadily to about +2 lb/sq.in at 20,000 feet I.S.A.' Usually the aircraft was operated in 'M' as we didn't often climb too high; if a high cruise was needed the above procedure was carried out.