I am afraid that as with any 'rule', there is never black and white, even if asserted as so by DFC.
3 Recognising an Emergency Situation
3.1 A controller may suspect that an aircraft is in an emergency situation when:
a) radio contact is not established at the time it is expected to be established;
b) radio contact is lost;...............
In this case, even in the event of the receipt of a Flight Plan by a transit unit, it does not automatically follow that they expect radio contact to be established (which negates point [a] above). The interpretation of many ATC units (and mine) is that radio contact would only be expected if the pilot had made an initial call and a follow up call had not been made when expected (asked to report passing a position, for example), or if the aircraft had been subject to a co-ordination message from another ATSU and then did not call on the frequency at the expected time. If it was otherwise, then the chasing around of people who didn't turn up (and were not obliged to in any case) would keep the Rescue Co-ordination Centres very busy indeed. Mmmm, now there's a thought. Bring that in and charge them all for wasted time. We could probably fund the whole ATC system .. and the NHS
If we do follow DFCs interpretation however, then there is also an onus placed on the pilot to contact each and every ATC unit on their Flight Plan every time their estimate changes by -/+ 3 minutes. These are the tolerances. Is that really what pilots (not to mention ATC) want ??
2 Aerodrome Procedure
2.3 Radio Equipped Aircraft – Preliminary Action
If an aircraft fails to make a position report when expected, the following preliminary
action shall be commenced not later than the estimated time for the reporting point
plus 30 minutes:
• Advise the ACC supervisor that the aircraft is overdue;
• Confirm ATD from departure aerodrome by quickest possible means;
• Ensure that an RQS message is sent.
Again, this down to interpretation. When do ATC expect a pilot to make a position report ?
Well, one scenario is 'when requested'. But you'd need to be in contact already for that, or asked to do so by another ATC unit. So in that case we already know you are in the system and have a firm idea of what you are actually doing.
Another is if it is a mandatory reporting point. But then you'd be on a published ATS route .. and have a clearance, and be in contact, etc, etc.
Bottom line is that for aircraft outside CAS, position reports are only expected by ATC in a limited set of circumstances. Hence our wide held interpretation that a pilot who simply files a flight plan for a transit and then is not subject to any communication with ATC (either directly or through another ATSU) is not expected to make a position report and thus cannot be overdue in making said report. That's why we as a system take no action on flight planned aircraft which don't turn up for a transit.
The entire responsibility in this case lies with the arrival airfield or the 'responsible person'.