Do I tell the mum her husband left their DD with me?

[Leavestumble]

Walking towards the park, and we pass a child from nursery. The children interact and I nod towards the child's father, who I do not know. He then says, "oh they look like they know each other, I'm just playing football over there, can you take her to play in the park and I'll be over in a bit". Then he just ran away without giving me an opportunity to respond. Over thirty minutes later, we all trot back across the field to track him down. He wasn't visible from the park. The child from nursery is saying, "I can show you where I live if we can't find daddy". Children are 3, almost 4.

Should I let the child's mum know?

I'm in two minds as not sure it is my place, and she must know how useless he is.

Unless OP said yes the bloke shouldn’t have run off. A non answer is not an answer.

I

This is what I want to put under at least 50% of Mumsnet posts

He shouldn't.
But he did.