I tend to agree with both the above, I think pilots talking to London Info, rather than to a more pertinent local ATC unit, causes an awful lot of incidents, especially once the 124.6/.75 frequency becomes overloaded.
Apart from the occasions listed by CM, I think the system could be improved by there being a published map with Flight Information 'sectors' evident, for any pilots to know exactly which ATC unit they should be talking to in a certain area, and for ATC to know who is likely to be talking to the aircraft, if anyone, in a particular area; instead of the current situation when the aircraft may be talking to any number of possible units, if at all.
Pilots would still be able to talk to no-one in the open FIR if they desired, but otherwise would know which unit to contact for local flight information. The main drawback is that units might require more staff to provide a system like this, and how would this ever be funded?
I've lost count of the number of infringements by aircraft who have been working London Info prior to talking to who they should be talking. Not saying it is L.Info's responsibility, of course it is the pilot's, but the system as it is does not encourage pilots to talk to the right unit at the right time, and a busy L.Info often wont be able to suggest they contact a more pertinent frequency.