Q, the Scottish word 'syne' is equivalent to the English word 'since' and neither have a 'z'. I can accept that pronouncing 'syne' as 'zyne' is a non Scottish usage, hence the suggested 90% of people in the UK but allow us in Scotland to comment on (not sneer at) the incorrect pronunciation. The example of 'loch' and 'lock' has already been posted. I think the latter is an inability of some English people to sound the fricative but the former is just laziness and an inabilty to accept helpful advice on how the word should be pronounced.