To think this isn’t cliquey?

This. Plus most people on Mn routinely misuse the terms introvert and extrovert, anyway. If you are socially confident and talkative, this does not make you an extrovert. If you are 'bubbly', gobby, dominate conversation and regularly make other people the butt of your jokes, this doesn't make you an extrovert either, it makes you a pain in the arse.

This is a classic example of how extroverts are demonised on MN and introverts are deep, worthy individuals.

Why were you " spectating", whatever that means? Speculating? If you felt that convos were being monopolised, why not join in instead of rolling your eyes?

Jamie's mum sounds like a dick. But both extroverts and introverts can be dicks.

I was on the other side of this back in early primary school days.

Invited out to large group meet ups which, over time became the rest of us spectating on the "clique" group who monopolised the conversations and you could see the eyes of the other mums rolling. At one, the extrovert mum introduced herself as "Jamie's mum, don't worry, he's not the bad Jamie" The other Jamie's mum was sitting next to me and blushed bright red. I knew her a bit, because her son and my daughter went to the same ASN playgroup, he's since been diagnosed with ADHD. The numbers dwindled because these parents were insufferable as a group.

The best thing you can do is leave the group WhatsApp. They will decide if they want to continue it and have meet ups.

I'd want to rely "there is no clique, just smaller groups of people who have become friends in their own right over the last four years. Absolutely everyone is welcome to this event, and I for one am very grateful to X for continuing to organise and provide these occasions for us"

She's being passive aggressive. Reply, this is obviously for everyone to get to know each other better.

This is a good response, kill her with kindness. Any response other than a thumbs up or a positive one is going to make her look like even more of an absolute idiot.

This. The OP has done nothing wrong, and nor, probably, have the vast majority of the Horror School Mums who operate a system of 'cliques', 'exclusions' and 'side-eye' in the opinion of the type of poster who puts far more of her energy into complaining on the internet into actually talking to other parents in the playground.

(My DS spent his first four years of school in a village school which was in fact rather unfriendly, as virtually all other parents had gone to the school themselves and had grown up together and weren't open to a foreigner who'd just moved to the area, but you know what -- it wasn't actually their job to befriend me. I was friendly, they didn't respond, and that was OK. Sometimes a person just doesn't gel with her social environment.)

Of course it’s subjective. But we don’t know what the majority of the other mums think of your manner and why. (And when I say ‘you’ I mean the collective group).

Im not trying to say you’re being a bitch, I’m giving reasons why the other mum (not knowing either her nor any of you) may have reacted strongly to a text.

Not you specifically, but your group. Or perhaps the organiser mum, since her message was the one targeted.

As I said, I don’t think YABU on the face of it, but subtleties matter in social contexts. Body language etc. 90% of communication is non-verbal. Maybe this mum has beef with the organiser mum.

Yes, pass the organising stuff to the moany mum.

Pass-ag woman doesn’t make herself sound good here, I bet there is a lot of eye rolling going on amongst other mums.

So what if people form smaller groups? I bet in your DC’s year group there are mums / parents who meet up in small groups having got to know each other from waiting around together at their kids’ swimming or football or ballet classes for weeks. But because you are a visible group as you’ll chat in the playground, you’re the target.

Has anyone replied to her? I’d say - “this group is for everyone and it would be great to have a bigger crowd come along… anyone who wants to suggest and organise a night out is welcome to do so.”

I think you should reply:

Obviously this is an open invitation for all class parents seeing as it’s being posted on the class WhatsApp group 🙄. I’m slightly confused about why you object to local people having friends and meeting up and why that’s surprising or offensive, particularly considering you were out having an exclusive evening with a school dad from the class and didn’t invite us. Laura has made the effort to organise class socials every year, they aren’t often well supported and it’s the people who don’t bother coming to them who are then offended when stronger friendships form. I will be suprised if she keeps bothering to organise any more socials after all this hassle.

Or perhaps, just from the person who organises the socials:

You know what, I’m done organising class socials. March 8th is cancelled unless someone else wants to take over.

Once again, depends how approachable they come across.

You're allowed to go out with friends you have made through your DCs school, not everyone has to be invited to everything. This other DM presumably also has working digits and could take the trouble to organise a whole class DMs night out if she wanted.

Some people see a conspiracy in everything, meanwhile they don't extend the hand of friendship or indeed cordial conversation to others, but like to harp on about Queen Bees and cliques. Can't they just accept that just as in other areas of life some people naturally gravitate together, as long as it doesn't impact on the DCs in anyway then it's nobody's business.

Why can't the other mum approach OP for a chat? Why does OP have to be the official meet and greeter?

It's give and take, isn't it. If you want to be included/invited or start to make friends, you have to be prepared to do 50% of the running. And so many on MN (and presumably in general) aren't prepared to do that. They expect everyone else to approach THEM, to start conversations, proactively notice they are standing on their own and come across, to make all the effort to include them.

Also agree that on MN "extrovert" means someone who answers the door and doesn't cower in horror from making small talk with a stranger on public transport or in a shop.

Why can't the other mum approach OP for a chat? Why does OP have to be the official meet and greeter?
If you cancel several times leaving people with booked tables, dont be surprised if people aren't chatty with you.

I am with you, OP. I am always the one who does all the running, and I have no time anymore for people who don't turn up, give one word answers or simply don't match my effort.

What you are saying is fine on the face of it, but nuances matter, and you all might be giving off a generally unpleasant and unwelcoming vibe at school times/events etc.

Perhaps this particular mum found it rude that you didn’t stop for a 5 minute chat with her when you saw her, depending on how your behaviour is perceived by others. You don’t have to be ‘friends’ to give someone the time of day when you presumably see her almost every day, maybe twice a day, and/or your kids have been in school together for 3-4yrs.

I'd reply "after four years of socialising, it's natural for individual friendships and smaller friendship groups to form. But this event is, if course, for all. It'd be great to see as many of you as possible"

Op, don't you know MN hates extroverts by now? You would have got sympathy if you had confessed to being terrrified of everyone at the school gates.

You have done enough and more for the flakey mums. Carry on in your supposed 'clique' and have a good time!