Got this one quite quickly. Squid etc was fun.

Good grid but for the final group it should really accept 'misspelled' or 'misspelt' phrases as a a correct connection as well as 'change one letter'

OK-we all know series like Horizon or Panorama but not one-off documentaries.

OK, thanks for the feedback Krista. For the record, there is only one one-off documentary in the 4 of that group and I gave that up with the name of it. The other one in the sequence formed a series and the red herring should be an irrelevance.
Regardless though, I've seen people criticise other grids for being "obscure".
Hello! Have you seen Only Connect?
A fair wall gives you at least one as an "in" and then if you perform the detection work in the correct order it becomes a mathematical exercise as much as one based on knowledge.
Does it matter? In the great scheme of things, no. It's a bit of fun. But there are no 5 star grids on the site, or at least none in the first 60 pages. So, either people are making shit grids or people don't understand the whole connecting wall idea because that's a ridiculous statistic. Walls should be judged for how they are constructed, not whether the player knows about the subject.
And that's my tuppence worth.

Well, the lack of 5-star grids is just due to how people rank, and how averages work. I usually rank things 5 stars unless there is actually a problem with the grid, but I assume lots of people will rank 3 as "average" and 5 as "really fun" subjectively. Factor in people having different subjective opinions, and it gets vanishingly rare for the average score to end up in the 5 range.

Odd then that I can buy hinges that have 5 stars after 237 reviews on Amazon.

A couple more factors on Amazon. First of all, they likely weight averages, so I'm not sure it's a pure mathematical mean. Second, people won't usually go to Amazon to give "mediocre" feedback; if you look at the actual ratings most have 5 stars or 1. Here, you are "forced" to give a rating after playing, so people who have middling feelings are more likely to weigh in.

I'd be curious to see the actual stats on rankings rather than just the mean we are given.

The informed group won't accept synonyms but otherwise I liked it.

Good grid, Pompeii was a bit hard.