Unfortunately I didn't get to see either of the monster birds of the day today. An Empidonax flycatcher species was discovered at Blakeney Point, Norfolk. Initially reported as either Alder/Willow/Least, then latterly as Yellow-bellied it was with baited breath that I waited for the photos to emerge. I've seen all 4 of the aforementioned species in Costa Rica and I think it looks more like Alder Flycatcher than anything else, however Alder/Willow are generally considered unidentifiable unless heard calling (and known as Traill's Flycatcher). My experience with Yellow-bellied Flycatcher is that they appeared more greenish overall compared to Alder/Willow and also had a larger, more distinct eye-ring with variable but generally distinct yellow bellies. Kevin Du Rose' excellent photo certainly goes a long way to suggesting Alder/Willow Flycatcher for me.
The other mega bird was a 1st winter female Northern Parula, this one was up on Tiree, Scotland, John Bowler obtained these shots of the bird as it fed in Hawthorns and Willows. According to Slack (2009), Rare Birds Where and When: An analysis of Status and Distribution in Britain and Ireland there has only been 17 records of Northern Parula (Britain - 14 and Ireland - 3), with a strong SE bias (e.g. Scillies, Cornwall, Dorset, Cork) with not many further records from other European countries, a northern mainland bird would be very much appreciated - please! When I lived in Costa Rica I used to get Tropical Parula in my garden, the parula genera has some stunning species, Northern Parula was a rare vagrant over there and it's one that I'd love to have seen there, just as much as I'd love to see one over here!
Hopefully something might turn up a bit closer to home!