Possibly ignorant question for the Brits and Aussies: If you're British, with, say a London accent, is it fairly easy to adopt a different type of accent within the Empire, like Welsh or even Irish or Australian?
'London' accent? I should slap you for that

Depends on how good your impressions are obviously but English dialects depends, it's easy to do an approximation of most but you'd rarely fool a speaker. Most Welsh dialects are the same, Scottish really depends on which area of Scotland you're imitating but you always sound like a tit, 'Irish' is fine if you're just doing a less-ridiculous 'Leprechaun' voice, have got away with it in the past, Australian I've fooled people with but probably wouldn't fool Doc, presumably it also has regional diversity so I just imitate Flight of the Conchords

That's just me obviously, seems to hold true for most people I know though.
And any attempt at a British accent is limited to sounding like Mary Poppins, which works fine in the bedroom but isn't of much use anywhere else.
Oooh matron
As a sort of follow-up question, can the average Brit tell the difference between various US accents? Watching a lot of British TV, I can hear a lot of different voices, but though I can tell that there is a difference, I couldn't really identify someone's point of origin from his accent the way I could an American. I would posit that most of the American television that gets exported features either Californian or Mid-Atlantic speech with occasional Texas and New York accents thrown in for color.
Yes, to an extent. I can obviously distinguish between your most stereotypical West Coast, East Coast and Southern accents, and then the 'subdivisions' within those. Depends obviously. You don't just all the sound the same at any rate which a lot of Americans have told me Brits do, though admittedly Britain's international cultural output heavily features 'Estuary (BBC) English'. Isn't there a Mancunian on Frasier or did I make that up?
It does annoy me sometimes when people use the term 'British accent'. You've got
this this (Jay-ell you'll like that one)
this this this this and it literally differs every 10 miles. People can tell which village I'm from in the local area
It's fine saying 'he's got a British accent' or whatever but when people are like 'I'm imitating a British accent' and then just speak like the Queen it fucks me off no end
Do Americans mix up English/Scottish/Australian accents or are they easier to distinguish?