I first heard of this Welsh art more than 20 years ago. Finally it has surfaced again. Sounds suspiciously like one of my native Serbian arts...

http://www.fatherdave.org/article/article_226.html

Then by gosh you should create one Cord. This is a perfect segway for you to be the founder/soke/grandmaster of the first authentic Welsh martial art. Let me know when you open your first school. I may want to franchise it. Please do NOT make anything even remotely resembling a kilt the traditional uniform. I know you are not Scotish but you could do it as some cruel test for your students to make them tougher.

The old Welsh culture shared a great deal with the other Celtic nations, but whilst Scotland and Ireland shared particular cultural/population exchanges, Wales had more to do with Cornwall and the Gaul's of France and Germany.
based on this, its entirely probable that some form of wrestling akin to cornish wrestling existed in Wales, and it is also known that the use of the sling for hunting and war was widespread in the area.
Its also worth pointing out that St.Patrick arrived in Ireland from Wales, and that William Wallace was of Welsh Parentage.
Cymru am Byth!

I didn't say where and how I'd heard about Lap Goch 20 years ago...

Suffice it to say, it appeals to my Balkan sensitivities - striking your attackers before they strike you; before they are even aware of your very existence!

I'm sorry to inform you that you are wrong, the photo on that site is in fact of a bunch of Morris Dancers about to do one of their handkerchief dances!

Morris Dancers on Wikipedia

I should know, I had nearly 50 of them arrive at my place a few weeks ago for a celebration, and they were a noisy and merry lot! Especially after all the mulled wine... and all those bells jingled a lot too!

Sadly, I know this only too well. I've not done Morris Dancing, but I've had to sit through it during countless demos at local fairs!!!

They actually do some stick fighting that looks a bit like arnis/escrima/kali - done stoned.