To not give her a lift?

How old are the kids?

DH is an activity leader and they would get into a lot of trouble if they allowed a child to go home with someone without the permission of the parent.

In this case it's even worse as the OP does not even know if the child was left at their home.

(Of course, these children might all be 16/17 in which case it would be fine)

Oh that's good that you have a way to pre warn that you won't be giving a lift. Honestly some people. I can't imagine just ditching my child and hoping someone would grab them. Crazy.

How did she kick your seat from the front?

It's too late now but you should have told them what you said on here. Plus made it clear that you had not been asked therefore no permissions exist. Had there been a reply yet?

Absolutely not.
It doesn't suit you or your child.

This is not normal behaviour.
This is CF behaviour.
The mistake was even doing it once.

Do not argue the point or explain.
Just repeat that it doesn't suit you.

Then cease to reply.
What awful people.

Definitely tell the person running the group exactly what happened and that you are responsible solely for your own child and will not be giving anyone any lifts.

Don't be surprised at pushback.

This happened to me years ago with a gymnastics class. I told the teacher that yes our children are friends, but no one has asked me to collect her?! And I don't even know where she lives. The teacher rang her mother. I stood with her and the teacher until her mum came. She looked mad, but didn't say anything to me. Who expects someone to collect their child without asking that person first?! The mind boggles! I found out later on, that she does this alot. Once you start doing it, it's hard to pull out because it's expected. Just post on the group chat, " Hi x, I'm sorry I can't give any more lifts." Be prepared that the teacher will assume you're taking this child home. Tell her at the beginning that you've never been asked to take him home, last week was a one off and that you cannot take him anymore. This allows her to contact mum, to ensure a lift's been arranged at the end.

This

This if something happened with no consent? Wowzers. Also, they could accusenyou of anything. You don't know these people at all. Safeguard yourself and child, and theirs by handing to teacher next time.

Just say we go shopping or go grandma's and it'd not an option etc.

Quite - and then took them to an address that was given by the child (and seemingly not verified by any adult) and then left them effectively home alone, apart from the random stranger who also lives there...

Was it left last week that you would be taking her home again?

Pre-empt the situation now.
Send a message now to say sorry I can't give xx a lift to or from the activity.
If pushed tell them you were never asked in the first place and if you had been you could have explained why it wouldn't be possible.

If you then turn up and the child if left for you to take home again, remind the leaders of your message and just leave the child with them. They will then contact the mum.

That sounds so wrong, so you took a child home from an activity, without the permission of the Parent?

So, I'd of taken said child to the teacher, told the teacher the child was under the impression I was taking him/her home and that there was no arrangements, no permission from said child's parents and I wouldn't be going that way today any way!

You licked it, so it's yours!!

Edited with this scenario,

The child just wanted to go home with you, so lied.
The parents weren’t home because they were at the collection point looking for their missing child!
Now you’re in trouble for taking someone’s child without permission!!

I would make an excuse so their can be no discussion about you being unhelpful in the group, which can get nasty. We always do xyz afterwards, had to go out of our way to take her home, what were you thinking just leaving her, we really can't be in that position again, your poor child left like that, lay it on thick and preferably in public.

@DreamingOfHotPotatoes cannot believe the mother did not ask you and just expected it!! sorry, but I might have considered leaving the child and the activity organisers would have sorted it out!

This. Just say you go to grandparents or something straight after, or shopping. say no in firm terms.

How was child getting to and from before?

You’re getting a lot of support for not taking the child home which is completely fair, but if you all know each other well then it’s not the same as a random child you don’t know. I don’t think I could leave a child without telling the parent I wouldn’t be taking them (yes I know she’s a CF), leaving her will just mean the organiser doesn’t get home on time. Just message her and tell her in advance.

I think I'll put a post on there saying I'm unable to give lifts anymore

Yep, do this - looking forward to an update!

Yes do that.