To report this major lack of judgment?

[FireUnderpants]

I had some work done on the front of my house. MIL asked the caretaker/oddjob person at her work and he said he could do it for a reasonable price. (He was meant to come earlier this week but was rained off, job involved cement, so came today even though I was out for a good few hours)

I went off this morning leaving him with a cup of tea, then arrived back to find the work almost done and my nephew sat outside with an unhappy builder.

SiL has told him Aunt Fire has got a builder round, so they turned up at my house to watch. Knowing I’m not there and the house is locked up. So it wasn’t even to visit. Sil sat in the car and then nephew refused to leave. So to stop the argument he said he would drop him home and sil wrote down her address and drove off.

Nephew is 8 and has learning difficulties. Builder is completely unknown to us. Mil is not really even on friendly chat level with him. I’ve paid and apologised to him and have told him I will drop nephew back myself after dinner.

Do I leash hell on sail as drop off or report this to ss?

@Pengggwn it would be a bit of a stretch but it could class as child abandonment which is a crime.

It was child abandonment. She didn't have the guy's permission to leave her son there and nor could she realistically expect him to give permission. What would have happened if he had to go to the shop for something?

@Pengggwn

Child abandonment laws are the legal rules which relate to a parent’s act of leaving his or her child without making appropriate arrangements for the child’s well-being and without the intention of returning.

She had no intention of returning,she did not inform OP that the child was at her house.
It might be debatable but i doubt many would agree that leaving a SN 8 yo child with a complete stranger for the whole day and rely on that stranger to bring him home are "appropriate arrangements ".

Where is the child now OP? Have you/dh seen the mother?

At the absolute very minimum I'd be giving SIL an absolute bollocking that she'd never, ever, forget. She is clearly not functioning with a full deck to abandon her child, SN or not, with a complete stranger and with so many dangerous items around.

Had I been in the buildren's position, I'd have called the police to report an abandoned child.