I think the problem is that a workbook or whatever is a bad way to start the day.
I don't agree you should do no work in the holidays, I think it depends on the child. Both mine do extra maths (learning times tables/ how to add up) in the holidays as their school, a perfectly ok state primary, is great at english and grammar but really quite crap at maths. So, it is our choice to do a few hours a week, either on the computer if we don't want to do it ourselves (MathsFactor or some such maths games site) or in person, to keep their skills up. That's our priority as a family, but I would't sit there with a maths sheet at 9 am, I'd try to build it in as a fun activity, and failing that, try bribery!
Don't start each day off in a bad way, forget about it for a week, then come back and just focus on the thing you want him to do: so reading/writing in a fun and interesting way, so writing about a day trip, or filling out a quiz in a museum, or playing hangman or reading a comic he chose himself, that widens his experience of learning, not offers a kind of second rate school experience.
Having said that, I did put my foot down with my 6 year old recently, she didn't like reading and tried to get out of the nightly reading for school, and I did insist she did it for 15 min a day (I said the school asked us to do that so that's what we need to do before reading our own story). It improved her reading no end, I just stopped giving her a choice, and sat out the minor paddies, and now she loves reading and reads at night under the covers! It was her inability to do it that put her off reading.
But in this case, let him choose what to read, let him buy things with reading involved (instruction manuals for example) but I wouldn't sit over a book for 1-2 hours in the holidays going purple, all he's doing is learning to wind you up, nothing more!