The Jaguar has an electric pump to give hydraulic pressure to the flying controls if the engines cease to do so. It should cut in automatically, but can be switched manually if necessary. Incidentally, when the engines do go quiet, it then soon gets very noisy as all the captions and alarms come on. But, as I found the hard way, the backup does work and the engines relight quite well when you get back down to a sensible altitude. Meanwhile, though you know it doesn't glide at all well, it does seem a long time going back down through the clouds waiting for that altitude.
As for the GR3, I seem to remember a high key (heading across the runway, 270deg to turn) at 14000ft, glide at 250kts, 9000 low key, and a round out starting at some other vast height. Must dig out the old FRCs (from the days before the procedure was deleted) to check.
