Feeling that these views were perhaps a little inadequate, I went back to the garden to search for it. You know how it is, somedays a brief obscured flutter just won't do. Thankfully, it seemed to be of the opinion that my garden isn't all too bad a place to hang around. Some thirty minutes after first hearing it call, I managed to pick it up again; flitting around a holly tree in the corner of the garden. What a little beauty, and that supercilium! Not quite as good an eyebrow as a Pallas's (honestly though, what is?), but better than a Chiffchaff by a long shot.
Okay, yes, the views were rather poor, but having only ever seen one before, I don't think I was particularly in a position to complain. Indeed, especially not when it was in my garden, and more so when you consider that my garden isn't in Norfolk - the 5,371km square YBW magnet.
Another stunning and unexpected addition to the garden list, and a nice way to procrastinate from procrastinating.