As we all know, the legal age of consent in the UK is 16; it's 18 for sending or receiving indecent images.
So if an under18 boy send a photo of his (or anyone's) penis to another under18 year old, he's committing an offence.
However, it's also an offence to be in receipt of said images or to have copies of them in any form.
(The same would be true of an under18 girl sending photos of her breasts but somehow it seems less likely that a girl would do that unbidden, whereas boys certainly do).
So what's the position for the recipient of such pics, if they were unwanted and unrequested? That young person suddenly finds themselves with an illegal image of a sexual nature of a child on their phone or laptop. Not their fault -- but where does the law stand? If they make a complaint (as they should do), do they have to surrender their devices as they contain illegal images? If they share the images amongst their friends (which I can well understand, to try to defuse the situation or embarrass the boy who sent them), in law they are guilty of an offence - in practice, what happens?
I'm asking because of adult friend of mine was bombarded with dick pics when she tried OLD, and it got me thinking about wider ramifications and in particular when it happens amongst school children.