Sorry Neil, but OS map references are very commonly used by the Emergency Services now.
When did that change?
About 5 years ago I was unfortunate enough to need to call myself an ambulance when on a canal towpath (crashed my bike into a bridge parapet causing what would be a minor injury except for that I went into shock and started losing consciousness, and ended up being taken in in said ambulance with very low heart rate and blood pressure due to the shock - and my blood pressure is normally on the high side). I offered them an OS grid reference, and they said they wouldn't know what to do with it - the thing they wanted was on-road directions, fortunately there was a pub, the name of which I knew, on the next bridge, so they parked there and walked up.
Or is it the case that call centres serving more rural areas are better geared up to this?
There really could do with being "an app for that" or a means of them easily remotely activating the GPS on a smartphone they are called from. (Yes, they can use cell-locate, but it's not half as good as GPS). Mobiles are great, but they have removed the ability of the emergency services to get an address directly from the number of the calling phone.