Must agree with Old Fella (sorry!)
Problem we had with the grenade valves that controlled the de-icing was that they weren't the most reliable in the world. It would have made me feel VERY uncomfortable trying to explain to the hierarchy why I selected it ON on the ground and the valve stuck open - indeed the Radome Anti-ice was de-activated in the RAF for this reason.
It's Catch 22 really. The more you used the system, the more reliable it became, but the hot air never did the Herc wiring a lot of good - especially as the aircraft aged.
And again, the Vickers hyd pumps were not good. When isolated they had a thermally controlled run-around circuit, so when re-instated often did not give full pressure (flow) immediately.
That's enough sensible stuff - I'm having withdrawal symptoms
