I don't know the answer in UK airspace but it must be legit in a more general sense because e.g. to fly VFR in Russia you supposedly need a Russian interpreter on board. I have also recently read something similar about Israel.
Just found this on the ICAO website: All pilots shall meet the language proficiency requirements when they fly internationally. The provisions contained in Annex 10 (Chapter 5, former paragraphs 5.2.1.2.3 and 5.2.1.2.4), which allowed the use of interpreters, have been withdrawn.
LPC might not be the correct word. I was referring to LP (Language Proficiency ) as defined here : OACI
Interesting to see that ICAO checks the box for the US as Language Proficiency compliant with no procedural fuss. Few US pilots would know they had been checked, but I think it occurs when you pass the check ride for your initial pilot certificate. No further checks are made, and I've never had a radio license (not required in the US).
No problem with flying to Canada or South America that I'm aware of - I think the license you need is a paperwork exercise, and I'm not sure if too many people actually do it.
To legally operate an N-reg (with a radio, of course) outside the US, you need a radio license issued by the FCC. Paperwork exercise and about 60 bucks.
In the US proficiency in English is a prerequisite for any pilot's license, hence no further checks once you've got your ticket.
Some of the Asian students in the US must have a hard time, assuming they are earning FAA tickets. I feel for them - at least the languages I've studied have similar sounds. Sometimes you wince hearing them make radio calls - reminds me of trying to make myself understood when asking for directions overseas, but at least I was stationary.
More or less on topic - eventually I'll have one of my German connections make a local radio call, with appropriate accent, using the aircraft type Messerschmitt :-)
Just for info, I am based in Germany and am currently organising a club flight around Europe. Some of the people wanting to fly only have BZF II - basic radio licence, only german language, only for flying in germany below 10.000 feet, BZF I - basic licence, in german or english language - hence in the past they did the flying and the person front right (who normally had BZF I) handled the radios.
However under EASA it's now changed. A single crew machine means that the PIC needs to fulfil all criteria for landing at a given aerodrome - means ratings for the machine, licence / medical currency AND language proficiency for the radio comms. The Bezirksregierung here told us that the PIC needs to have all the relevant capabilities and licences, it's NOT okay to have one person fly (e.g. with BZF II) and another one handle the radio (with BZF I) - the plane itself has been declared as "single crew" hence the PIC needs to be able to demonstrate the ability himself, not to point to the second person and say "he's working the radio".
Now, if the PIC does have the necessary language skills, nothing is stopping the PIC handing off radio communication to the person sitting front right, just as long as BOTH have the required skills / licence / language proficiency......
I doubt this very much.
Yes, a german pilot does need to have english LPC if going abroad. He cannot substitute a lack thereof with another crew member who does have it.
But re the radio license, they are wrong. A german with LPC english but without BZF1 or AZF can fly abroad if he has someone along who has it and if does the radio part for him. This is the way it has always been. The introduction of LPC requirements does not change this concept. Typical case of a Landesluftfahrtbehörde interpreting things their own way. The root of the problem is that, as you mention, they "invent" that a VFR private SEP cannot be flown by a crew of two. An old chestnut here in Germany.
It is important to distinguish license privileges and radio operating privileges, two things which, at least in Germany, are rather independent of each other.
P.S. Realistically speaking though, in the german context, it is rather unusual for a pilot to have LPC english, but not at least a BZFI, so the above case is rather a moot point.
Isn't this a theoretical issue that really will never matter in practice? So long as someone is along who is licenced and can handle the radio - who will ever care?
A friend of mine called the FOCA (Swiss Aviation Authorities) and they were unambiguous: In EASA land, PIC must have all the licenses, medical and privileges. The pilot handling the communications must be PIC and you cannot be PIC if you don't have the required licenses of the airspace you're flying in.
So you cannot have another pilot handling the radio for you in a single pilot airplane.
From what I understood, the situation was different pre-EASA.
Whether it is legal to have one PIC without LP for a particular flight and a second person with the radio authority is very questionable. The PIC is responsible and that should include being able to understand what is going on the radio.
However, the German law does allow for a non pilot to perform the radio. This is § 32 of LuftBO. This provision states that for IFR, there must be a crew of two pilots. For aircraft with not more than 9 passenger seats, one pilot is enough, provided that there is a 2nd person "authorized to perform the radio communication for instrument flights in the English language" or alternatively a working autopilot with course and altitude holding.
The conclusion is that mastering the English language and having a radio certificate for IFR is worth as much as a simple auto pilot with course and altitude holding 
