Being told "Remain Outside Controlled Airspace" is not a clearance. I fact it is reinforcing the fact that a clearance has not been issued and one must not enter controlled airspace.
On the Class E issue, Once can enter under VFR without clearance and must remain VMC at all times. If IFR then one can not enter without clearance. So, if departing into or towards class E, if one decides to depart VFR and pick up IFR enroute, one must remain VMC until ATC issue the IFR clearance.
That is diffeent from the Class G case which started this all off...where in the case of say the London TMA, one can continue IFR remaining outside controlled airspace until such time as a clearance is issued.
One point to remember with regard to the London TMA is that if one decides to continue enroute below the base awaiting IFR climb, this can in some cases complicate matters because the flight while not in receipt of a clearance will be moving from sector to sector thus slightly complicating the coordination process. Thus it can at times be easier if the flight holds while awaiting clearance...although this varies from situation to situation and from day to day.
However, what must be remembered is that for an IFR flight intending to enter controlled airspace, a SLOT may be issued by CFMU.
Going back to the flight departing and remaining in Class G, as W Collins correctly says, one can be IFR for a number of reasons and provided that one complies with the minimum height rule in descent towards the destination can be FIR from farm strip to farm strip non-radio.
I also agree that possible with the exception of some choke points below the London TMA, one is more likely to have an airprox in VMC than in IMC.
However, the rules require that except for a local flight the combination of forecast and actual weather must show that the flight or portion of flight can be completed in VMC if the flight departs VFR. If the end of the VFR segment is dependent on receipt of a radar service which is not guaranteed, where is the end of the VFR segment?
There would have to be some point where the pilot would say...if I don't have a radar service by XXX, I'll turn back.........however, given the conditions, is a safe VFR return guaranteed?
One can depart IFR from any aerodrome. Remember however that the relevant part of JAR-OPS applies to all flights and sets the weather minima!!
On flight planning...don't forget the Z and Y flight rules!!
Regards,
DFC