And as for Cosher Bailey, there is this glorious verse
There are lots of honey bees
and they swarm around the trees
The go into Llangollen
and the suck up all the pollen.
So of course you have to pronounce Llangollen correctly and rhyme pollen with it.
For those of you who don't know, ll in Welsh is pronounced like the ch in loch in Scottish or the kh in Arabic. There is no such sound in English, it sounds as though you are about to expectorate.
In Welsh the stress is on the penultimate syllable and in LLangollen the e is close to the English i as in fit.