Identification assistance for bird spotted in Oban, Scotland

Hello RSPB Forum members,

I was in Oban, Scotland on May 8th, 2024, and spotted and photographed this bird (see attached photos).  I can't find anything like it in my field guides on in the Merlin app.  It might be an immature bird, but May 8th seemed a little early for fledglings.

Any help with this?

Thanks,

ScottW