Just returned from a trip to the USA, and what struck me in the light of this thread was the number of incorrect read backs, and misheard frequencies, along with quite literally dozens of: "........I missed it - who was that climbing to '4 oh oh'?" or ".......sorry what heading was the Cactus on?" type of confusions I heard, because just about everyone was using non-standard phrases.
Non standard to exactly whom? Non standard perhaps to the residents of Little Britain, but so be it. The world doesn't revolve around your axle. Do please engage your translation circuits ( similar to others do when flying in UK airspace) when exiting the M25 orbital.
I have never experienced ambiguity when operating under US ATC. Conversely, I have never experienced complete certainty as to the meaning of the given clearance when operating in UK airspace. Even "cleared as filed" doesn't mean cleared as filed. We just read it back and do what we think is required. When heading west, there's a sigh of relief when we drop from radar coverage and the mess is behind us.
Shanwick on 123.95 is a good thing.
Best not to mention points further east.
My ultimate responsibility is that of getting the aircraft on the ground before it runs out of fuel, and that's what I do, regardless of the jumbled- up lingo.