^^This.
I've driven down the hard shoulder on various motorways on many an occasion but that's usually on the way to an RTC on the same stretch of motorway further up ahead and the traffic has tailed right back and ground to a halt in both lanes.
And as another ERDT Fire Service driver, here's another little tip for you folks. Be very careful when a fire appliance approaches from the rear and passes you. Don't get caught up looking at it as it goes by, pulling out again after you have given way, without checking your mirrors to make sure it is safe to do so. Reason being is unlike Ambulances, a lot of fire appliances work in pairs as it were. We have PDA figures ( pre-determined attendances ) which will send more than one appliance to certain firecalls. Or an appliance and a special appliance such as a heavy rescue unit or an aerial ladder platform.
We see if regularly, Joe Bloggs hears a fire engine, clocks it in his mirrors and slows down, moving over to let it past. He stares at it as it makes its way through the traffic and he then pulls out again without looking in his mirrors. Only to get a blast from a bullhorn as another fire engine appears behind him. You can with experience, predict almost every single time this is about to happen, by observing drivers and their actions on the road.
Even worse are the ones who see the car in front indicate and pull over in order to let us through but they themselves then overtake the guy who has seen us already!!. But that's another road I won't travel down in this thread as it's not exactly the topic.