boomerangben:
I refer to my previous post:
"D&D will always be the first to call out the SAR facilities" (i.e ARCC Kinloss)
as I don't think anyone else has the authority to do so in this case.
The London FISOs (not controllers) are not allowed to have access to a radar for reasons of licensing, and they have to walk/run some 30m to get sight of one, which would mean abandoning the frequency on which you were telling them your problem. In the scenario described, you could of course call a Mayday and give position reports and maybe anyone in your vicinity might come looking for you. Ultimately however, London Info will pass your position report to D&D and they will try to locate you. Thus, as I have indicated, a call to D&D by you will get this process moving faster.
D&D will have no problem in letting London FIS know that you have left the FIS frequency.
By the way, London Info have no DF equipment available to them (not least because of the multiplicity of TX/RX sites they use). I don't know about the exact accuracy of the D&D DF triangulation over the Channel area, but I'm sure someone will.