Ok, sadly I have some personal experience of this.
I lived overseas for a number of years, and DD spent her primary school years there.
A couple of years ago she told me something a friend had disclosed to her that indicated sexual abuse.
I worked at that time in a role that basically meant you should report ANYTHING that is potentially controversial i.e. blackmail material. I reported the info through work channels, they said they would report to the police. The uk police (Met) contacted me for further info (I didn't have any, DD could describe the block of flats but not the address and no further info about the perpetrator).
Months later my tenant overseas contacted me saying the local police had turned up asking questions, and leaving a contact phone number.
I phoned, got voicemail, and left my contact details. Never heard anything.
Sooooo...
There is a limit to what the uk.police can do, or what someone aware of abuse can do. Of course any individual should report what they know. The uk police should pass on any info they know. But sometimes the 'knowledge ' is very vague. And no-one can ensure the overseas police take any action.
Sadly.