not sure how many people you think would know the 4 islands of Tristan de cunha! or the names of the 4 rings in wagner ring cycle.... some may but we are talking very very few. Incredibly tough grid

Yes it was fiendish. Got two lines and one connection. Aren’t we due a few more Korma Rants :)

Too tricky for me.Only got 6/10. Opera group was easy, portico was harder to sort from the others.Knew the Tricki-Woo and inaccessible line links,just couldn't separate the groups.good

Any fool can choose four lists which require VERY specific knowledge. How about making a grid that you solve from first principles e.g. by placing hidden PATTERNS, or something a little more stimulating, so that there's something to 'work out' using your brain, rather than simply recall. Your grids are just endless lists. Have you seen Only Connect?

Tricky indeed, woo was the give away for that line.
Got two other lines.
Tristan was a good red herring.
The other 4 were obvious.
Didn't know the Gough line.
You win 10 -7
Thanks for posting

Not a clue about TdC, but the rest were easy.