One can debate this for ever, but nobody is going to change current international IFR practice, which is "cleared to destination".
4.5.2.2 When a flight plan specifies that the first portion
of a flight will be subject to ATC, and that the subsequent
portion will be uncontrolled, the aircraft shall normally be
cleared to the point at which the controlled flight terminates.
is obviously unworkable on any non-trivial flight.
The UK might have an excuse if it was not for its tightly compartmented ATS system with a lack of radar service in the lower bit, and if it was not for the stupid CFMU routing system which until very recently was sufficiently impenetrable to enable the likes of Jepp to charge 3 digits per month of working out the routings, and which remains impenetrable today to anybody but a small crowd of dedicated hackers
But there is NO excuse for a transfer to London Information without informing the pilot that his IFR clearance has been terminated.
Almost every time I get chatting to a pilot at some airport (and outside the UK I fly almost only to international airports, because of the Customs issue) it is apparent that he hasn't got a clue how to work out CFMU routings, and usually hacks around until he gets something accepted.
I think that staying in CAS is the least of his problems....
There are other implications e.g. if one gets dumped out of the IFR service then one should carry VFR charts for the area. Almost no IFR pilot carries VFR charts; most countries in the world don't publish them anyway (one cannot regard the TPC/ONC charts as adequate, not least because they don't show CAS and have not been updated for 12+ years) and the VFR chart collection for a flight across Europe would be 10-20 charts and would cost about £200-300. Pilots routinely carry VFR charts only if on a Z/Y flight plan. But a pilot "transferred" to London Information most definitely needs the UK VFR chart.
The UK is simply out of line with international practice, but doesn't want to admit it because the required changes cannot be easily implemented within the current privatised-ATC / working practices structure.