This typo made me giggle because slag is slang for slut/whore.
LOL oh how did I miss that? I really need to pay more attention, I would have fallen on that with gleeful abandon had I noticed
So in short, only sparingly and jokingly unless you're from London? 'Tis a shame, because I think it sounds cool. As for the word Briton, I know what for instance the Scottish think of being called English. One shouldn't anger people with claymores. :P
English is kind of a shared language in these islands. But...it is a conquered land. Many waves of invaders and immigrants throughout history and prehistory have shaped the political geography and language, like many countries, but Britain even more so.
The 'natives' of this land are the Welsh, Cornish, Manx, Briganti (a Northern English tribe), Irish and...the Scots are a bit of a complicated matter, as are the 'Irish.' Successive waves of people have colonised Ireland in the past, with the fair haired Irish being only the most recent. The Irish and the Scoti swapped places a lot in prehistory too, as there was much travel and trade over the sea between them. And ofc the Picti arose in Scotland during the Roman occupation. Latys not even mention the Romans. The modern Scottish are currently British, but that may change as the Union collapses and political power devolves even more. They are, however, definitely NOT English, any more than I am Scottish.
It's all very confusing, and many Britons (or at least the southern English) largely have no genuine ethnicity: the English are a mish-mash of Welsh, Angle, Saxon, Jute, Danish, Latin and Norman, all subsumed into a background of regional accents. The Welsh are the real natives of that part of the land, but they were marginalised by the Romans and later by the Saxons, English and Normans too. The term 'wales
' means 'foreigner' in the pre-Roman Brythonic tongue and is what the Romans called the natives, that then slipped into the native parlance to refer proudly to themselves! It's no wonder there is Welsh and Scottish hatred for the 'English.' They have stronger ethnicity than the bastardised English, who have pushed them out to the margins in the past.
What often galls me is the utterly inaccurate concept of being 'English' touted by many nationalist militants. They appear to have little concept of exactly where their supposed ethnicity originates from, which is largely from the Germanic tribes in the post-Roman period. The 'English' as much as anyone are descended from immigrants and belong here no more than any other wave of colonising invaders.
And even before the Romans got here, there was far more mixing of cultures and travel than is commonly realised. For example, many people think of the Bronze Age barrow builders as natives to these islands, however most of that culture was influenced by the continental Beaker people and may even have directly supplanted the pre-existing Neolithic populations.
Sorry, I got a bit carried away there!
I personally wouldn't imitate someone else's dialect or slang in polite conversation. If it was done to me, I'd find it disrespectful and even offensive. The exception is when you know someone. I had a flatmate from N. Ireland once who expressed himself solely by using the word 'fuck.' We all used to take the piss out of him relentlessly about that and his accent, but we could get away with it. LOL he just told us to "Fuck off."