the reason some people pronounce skonn as scoan is socio-economic: post ww II was the start of the rise of the middle classes from those previously considered working class.
the pronunciation of scoan came about as an affectation used by some of those who had 'moved up' and were keen to distance themselves from their working class upbringing (the use of scoan, ironically, gives the game away of course); think annie walker (coronation street) or hyacinth bucket (keeping up appearances) as stereotypical examples.
today the use of skonn/scoan does not delimit class in the same way, but does hint at where their family have come from, so to speak.
oh, and it's skonn…