Only got one group, very hard

Cool grid!
I thought the history row was too tricky though!

For younger viewers that is!!

Any ideas why this is down to a rating of 2.5 stars? OK, it's hard. OK, some may not like it. But what's wrong with the quality?

Responding to the quality question ..... I think some would have rated it higher if the answers where written as numbers (e.g. 4) rather than letters (e.g. four) ... I realise this makes linking one of the groups much harder to solve.
Omitting the 'nineteen' before the war years may have irritated some.
Coupled with the fiendish level of difficulty maybe that is why the quality was marked relatively low

Thanks, Si, for your thoughts. I wanted solvers not to know if a clue is a word or a number - so they could not be shown as digits. Good point on the 'nineteen's. Your last point - it bothers me that people might mark down the quality because it's too difficult (that's what the difficuly rating means!). I also think that quality is marked down if someone does not enjoy it. Unfortunately, Puzzgrid has no rating for 'Enjoyment'.

There is another, similar grid 43812.

you are right about marking down for other than quality reasons

A clever grid.
Maybe people who marked down the quality were looking for a normal grid (whatever that means) and had not appreciate the cleverness of using numbers as words.
It would be good if puzzlegrid let setters add a comment ahead of their grids. That way solvers could be told if it is trying something unusual.