Was I in the wrong? Neighbour issue?

You shouldn't have made that assumption on their behalf.

You could have invited them and left it up to them to decide whether to be in the group or not.

Apologise and offer to add her.

YABU. If you were setting up a group for a specific area then you should have invited everyone to join. There's no obligation for them to accept it but they get to make that choice, rather than you making assumptions.
I would imagine that your neighbour probably thinks you deliberately excluded her and is wondering why.
Go and speak to her, explain your actions weren't anything malicious and let her know you made an error of judgement.

YABU for saying new build estate where I live and YABU for making groups and if the group was necessary then YABU for excluding people then wondering why they are mirroring your rude behaviour.

I live in London - our group has been brilliant. We regularly post messages to warn everyone when our local parcel thief is out and about, or someone has been trying the handles of cars. When a car/van/bike is stolen we can all check doorbell footage. If anyone has received a delivery that has been delivered to the wrong address… the list is endless. It’s not compulsory, obviously, but even the HMO’s tend to join it.

edited to add I was meant to quote Helpmegetthroigg who said
“The whole idea of street WhatsApp and Facebook groups baffle me”

Jesus you all need to grow up.

You were BU to not ask her to join if it’s a group for the neighbourhood

She’s childish and pathetic for seeing her arse over something so trivial and petty

You're being utterly unreasonable. You deliberately excluded your neighbours from a neighbourhood group based on your own prejudiced assessment. I wouldn't speak to you either.
Go round and apologize, you got this totally wrong.

You all sound very childish.
Talk to them and sort it out as a mid-reading of their wishes to remain private, and apologise if you caused upset.

I can’t even believe you are asking if you were unreasonable! I mean, surely you can see that you have been. Really unkind to create a group and exclude some people, bullying behaviour.

You had the perfect neighbours! Now you have messed it right up- it should have been her choice to join the group and engage with it as much/little as she liked.

Our neighbours are older, we have very little in common but we are neighbourly with one another- take parcels in, remind one another of bin day changes, water the gardens on occasion. Normal neighbourly stuff. We have a small amount of chit chat now and again. It perfect because we can ask for favours but we are not mates. We have helped them chop down some trees this weekend, last month they looked after our greenhouse plants while we away for the weekend.

Honestly. Go an make your apologies and he honest!

You should have asked them and given them the choice to say no. You come across like the clicky school mums that i tried my best to avoid.

Agree it's a reverse, can smell them a mile away

How rude of you to assume. You invite them and then it's up to them to choose to join or not.

Oh dear.

This ☝️

It’s ridiculous that you made their decision for them. You’ve effectively created a neighbourhood watch group and ostracised them (any others…?).

Doing other people's thinking for them rarely ends well.

@hallogalorrr that wasn’t your choice to make you should have extended the invite and made it optional and said you would understand if she didn’t want to join

you didn’t and excluded her and she is rightly upset

You asked yourself the wrong question. It's actually irrelevant whether they would want to join the group or not. The question should not be 'would they like to join'. The question is 'would they like to be invited to join'. A no brainer. You have been (possibly unintentionally) very rude.

I am calling "reverse"

YABU if you really did do this
YABU for doing a reverse

I didn’t think that she would want to join

Same as the 'I didn't think you'd want to come so I didn't bother to invite you', no one has ever said that and genuinely meant it, so it's pretty obvious you didn't want them in your little group.

I'd probably blank you too, and I'd definitely stop doing favours for you.

Rude.

You might as well be honest about the reasons you didn’t want her along, nobody can ID you on here & if not honesty with the anonymous internet, then at least be honest with yourself. It doesn’t make sense to say she’s both chatty & keeps herself to herself, if the other neighbour was invited then what got them included? Extremely chatty? A little tap dance for you as you walk up the garden path? Why are people up to 3 streets away invited but not this one? Are you all extremely close bar this one neighbour?

How did uninvited neighbour even find out about the group?

oh, the age old "assumptions". If I were her I would´ve said, oh hi galorr I hear you´ve created a neighbour whatsapp group, I´d like to join etc etc
But I think she is a bit passive aggressive, so is in huff mode.
You also have blame, as you should not make assumptions. You ask all, and they will say whether they want to join or not.

Sorry but that’s batshit.

You invite everyone equally and it’s up to them whether they join, surely?!

You assumed but didn't actually ask.