2donkeys / wcollins
Interesting - I didn't know that you get the non-ATC airfield radio operator to telephone London Control (or who-ever else). That's news to me. What if it is a farm strip? You presumably call them yourself.
Of course none of this means anything safety-wise because at best one is going to get procedural separation from known traffic. In a free for all airfield you won't get even that.
So, given that departing "IFR" is likely to mean absolutely nothing, why not depart VFR and change to IFR on the first call to the proper ATCU? I suppose having a pre-assigned squawk saves a bit of time
Having been to plenty of free for all airfields, I think the chance of a collision in the conditions described is far less than on a clear day!
It's been an interesting debate on terminology