Worried about possible child abuse

Yes, phone social services and explain the case.

Yes, as above.

Yes, do this today.

Yes, find the number for your Children's Services Department. It will help if your friend is prepared to give her name and former relationship as that supports the referral. The department will not pass that on. Your friend should stress she wants the matter to be treated as "an anonymous referral"

If in doubt, you must report child abuse, suspected or otherwise.
There is no time to lose. I would never forgive myself is a child suffered because I dithered.

I was very much involved in child protection in my teaching job, the mantra was report, even if it is just an instinct.

Definitely agree with the other posters yes you need to report it and as soon as you can That is not acceptable
I wonder why the adult abused child hasn’t reported it themselves

Message withdrawn at poster's request.

Immediately.

How old are the children of under 5 she can contact the HV, does she know what school they attend she can tell them, SS and NSPCC

As an ex-social worker specialising in Children & Families, my advice is to call your local social services. They are well used to adults approaching them, who are unsure or trepidatious.

Alternatively the NSPCC www.nspcc.org.uk/ has a helpline for adults with concerns about children. They will advise and help, too.

You have taken the first step by raising this issue here, well done. You now need to take the next step.
Good luck.

Report immediately, children’s services will investigate even if it’s just a suspicion.

Report asap to local Childrens Services. You can tell them you wish it to be anonymous.

Do not wait Call protection services. Every day that child spends in a dangerous setting robs him of his human dignity to say nothing of the mental and physical pain. This is an alarm for a concerned adult to come to his aid.