Many thanks, CaroleW and rosinish for your replies; my enquiry was entirely whimsical, the result of realising that many Welsh placenames have 'the' before them, whereas in England the practice is very rare, with particular thanks to CaroleW for the link which confirmed my expectations. French names provide several examles - le Touquet, la Baule, le Mans, le Havre etc while Den Haag in the Netherlands is well-known. Italy and Spain don't seem to be too fond of 'the'.
Totally inconsequential, but diolch for your interest.