Just wanted to thank everyone (well almost everyone) for their responses.
I've definitely learned a lot about how different families operate. There seems to be a very extensive spectrum. At one end some posters said they do not even know which day their child leaves primary school. Others said the parents (both?) were away on a cruise when their kids finished primary. At the other end of the spectrum there were families who try and make as many school events as they can,have traditions of celebration meal at the end of each school year not just Year 6. Some DC want parents there, some don't. Some DHs who are able to be there on the last day and who will have a tear in their eye.
For me, when work permits, I like to be at the being around end of the spectrum for as long as the DC want it. I agree with the posters who think moving on from people and places you've been around for seven years does deserve some kind of nod.
I think our primary school parent friends must be unusual as most of their DC are very happy to have the parents around (if work permits). At fairs and stuff the adults hang out together and the children do their own thing.
Having read this thread I can see and accept that DH is more towards the other end of the spectrum to me. It's not right, or wrong, just different. I still think he should have remembered when the day was and so does he. However remembering when the day is and choosing to be around are different. If he prefers to go out after work in town with his mate then ultimately it's his choice. In the same way it's his choice if he joins us over any part of the summer with our various camping trips and family visits etc.
On the single Mum point. I have vast experience of this with my now adult ones! I don't think both parents have to be around on the last day of primary school. I brought up one of mine with no Dad involvement at all- period. Families are all different.Some people understandably just can't be there as they are the sole breadwinner and have to work then.
But...If I'm bringing up a child together with some one (and I am with this last DD ) I'd prefer us both to remember a date a week or so away when primary school ends. I'm not particularly flaky and in need of support, as I've done the whole parenting thing on my own before.
I originally posted on here because whilst talking to DH about it I went to get a cup of tea and he fell asleep, which is why I posted. Even though its a snake-pit, I have learned loads.
And to those also with Year 6 DC hope they transition to secondary happily, settle in quickly and that they make loads of new lifelong friendships.