Article from the Yorkshire Post (https://www.yorkshirepost.co.uk/heritage/iron-age-shield-found-in-pocklington-is-one-of-most-important-ancient-finds-this-millennium-1-10137418). Nice stuff about the shield. Interestingly, evidence of possible battle damage, which would suggest these fancy shields were used, not just displayed.
The bronze shield-facing is made up of two crescentic plates around a central boss, which is very similar indeed to the nearby Grimthorpe shield - though it has been suggested that the latter is an assmblage of bits rather than a complete shield (https://www.academia.edu/39288005/The_Grimthorpe_Shield._Object_or_assemblage). Looks like it's a local fashion.