"But the identical spelling - Clazie - is now found in France, the Netherlands and Berwickshire, all in the space of 70 years. That changes the perspective?"
See, I guess we differ there as I'm not so convinced it does. It might just as easily be a reflection that this is generally the date when records start appearing, if you see what I mean. It could be the surname Clazie/Clasie was common in all these places long before it first appears in written records, but in most European countries it's a similar story, registers before the 18th century tend to be fragmentary if kept at all, and before the 16th century largely non existent. Of course it could have a common origin all the same, Norman or perhaps even further back and it's a Germanic patronym with related Frankish and Saxon forms. If it was in use as a forename too that might suggest the latter.
In regards Jon Clazie's 16 shillings, perhaps the drink was just a courtesy for the delivery man rather than the actual fee? Still according to the old money to new converter tool on Ancestry 16 shillings in 1665 is about equivalent to 65 pounds in today's money, which even at todays exhorbitant prices, would buy me a good 18 pints of my favourite tipple at my local watering hole, so it was a good drink all the same!
It's also worth bearing in mind he delivered the Bell 16 March 1665. The second Anglo-Dutch War had broken out 12 days earlier, and would last over two years until 31 July 1667. This was primarily a naval war, a series of pitched battles between the British and the Dutch at sea. This may have made it impossible for him to return if he had bought the bell over before hostilities broke out. Maybe after two years stranded in Berwick, he'd found a girl fallen in love and decided to stay put even when safe to return?..Oh well it's a pretty picture I paint, but could bare no relation to the truth. Well you did invite wild speculation at the start....hope I've delivered that at least!