It would be good if people checked their 'facts' before posting.
The case of the two Aylesbury detective constables caused such an outrage that the then Labour education secretary instructed Ofsted to stop pursuing parents who shared mutual childcare arrangements for no other reward. That was ten years ago.
Ofsted’s guidelines on requirements to register with them have since been amended accordingly. You do not have to register with Ofsted if:-
...you provide childcare for less than two hours a day (even if doing it 'for reward')
Or..... if looking after friends' children for less than 3 hours
Or..... if looking after children in the children’s own home
Or..... if you receive no money, vouchers, gifts or service in return (ie not 'for reward')
These do not all have to apply. You are exempt from registration if any one or more applies.
That said, I would recommend using a registered childcare provider.
I’ve seen way too many of these 'friendship arrangements' fail. They can work, but they frequently don’t. They can put undue strain on the friendship, the children and even on extended families in all sorts of ways. I’ve known this sort of thing to ruin relationships. You have no guarantees and no comeback when the other parent lets you down. It will be nigh on impossible to find a short notice alternative when the other parent falls ill or suddenly announces they aren’t available next week, etc, etc. You name it, I’ve seen it.