It should be fairly easy to find the groupings for this one. He connection for one of the lines is harder than the rest and requires some additional knowledge, but the rest should be very easy for anybody who's well-versed in English Language culture.

Missed the bowling and horror links but otherwise straightforward.

Same as Orlando, but correct answer for the Brillig group was marked incorrect.

Ditto!

7/10 got me on the Cranker line.

Excellent grid, really, really difficult!

Not accepting "writers" for "authors" is a bit pathetic... otherwise this was quite good.

One line then 2 answers this one was hard for me

A very enjoyable grid - thanks.

I disagree about the difficulty: the only group that is anywhere near easy is the 'shop' one.
The vast majority of people will have no knowledge of Jabberwocky, nor will they be familiar with bowling terminology. Two of the horror authors (Jackson/Machen) are pretty obscure, making all three of these groups quite/very difficult for the average person (although admittedly they will be much easier for someone who is well read and also bowls).

Nice to see the Jabberwocky. Two horror writers and bowling terms too slithy.

The word famous is used very loosely here - by which I mean it's twaddle.