Mostly, I would not have been so eager to sort this thing out as much as I do right now.
When hearing this bird, I just continued, birding the area, being patient to sort this out later. Not to keen on it at all.
Frustratingly, I heard this unknown call with the bunting, passing by and kept the crown stripe, headpattern and stripes over its back as well as its streaky upperbreast and difuse yellow ish underside fitting for Yellow-breasted Bunting.
And why?..12 th of September on the isle of Vlieland, the exact same location, I had a smallish dark sooty faced Bunting with large white upperwingcovertpatches, dark backed with little contrasting stripes, very little white in its outer tailfeathers and immediate recalling sharp pennetrating tsik call (not so blunt as the subject recordings). Had the calls first (with 'see' notes as well), expecting a good bunting. Bird came a bit later.
With this kind of ID problems intermixed, I feel all sooty myself.