I don’t think size matters for this kind of thing — if they grow, and you didn’t enforce action when they were small, you don’t have much claim when they’re large (and the violation is worth more, and they’re more established in it, and they’ve built more of a brand around it).

but yeah Oaty vs Oatly might have been reasonable but PureOaty is quite the stretch

》No they don't. This is a common myth when it comes to cases like this.

This is the UK, where digital reproductions of public domain documents do get a copyright. While I agree they overstep here (especially that a regular customer would see the two products differently), IP laws in UK are much more sensitive with these issues.