Harmonium: are you sure there is a Scottish fiddle style, and an Irish fiddle style, but no English fiddle style(pre Swarbrick)? I suggest you have a listen to various traditional fiddle recordings. You will find there are many traditional styles in Scotland, many in Ireland, and many in England. You can't of course say how many distinct styles there are, as they merge into each other. SE Scotland merges into NE England and so on. But there certainly isn't(or wasn't) one style in Scotland that lasts from Lerwick to Berwick, and one in England, which miraculously changes at the border and lasts all the way down to Dover. Folk music doesn't work like that, though radio and arts funding are trying to make it happen!"
You notice I have left Wales off the list. To the best of my knowledge there are, surprisingly, no recordings of Welsh traditional fiddling.There are many theories why this should be!