My b/friend just described someone as"she's got a face like a bulldog chewing a wasp", while never having heard this expression I wondered its' origin?
It's been around for quite a while. Basically bulldogs are not blessed with the most aesthetic of facial features, and a face contorted by chewing a wasp would make it look even more unattractive.
The phrase definitely seems to have its origins in the UK (which, given that the Bulldog is regarded as a British breed, is unsurprising) but its exact origins seem to be unknown. One website says that it's Scottish but I favour the one which claims the phrase for Lancashire.
It's probably just something which one (unrecorded) person thought of and then his mates, liking the phrase, copied - so that it eventually spread throughout the UK.
Your response to Les Dawson impressions is better than Les Dawson's then, Toni ;-)
I once met a guy who taught LD's kids. When Les walked through the door at a parents' evening, the teacher couldn't resist greeting him with an impression of himself (as in the Cissy & Ada sketches with Roy Barraclough). Mr Dawson didn't say a word. He simply turned round, walked out of the door and was never seen on the school premises again.