Well it obviously wasn't a Blackburnian Warbler or a Mugimaki Flycatcher, but I'm still not sure what my auntie saw in her garden the other day. Further 'pumping' has elicited the following additional information (bear in mind that she originally said the nearest thing in the book was Pied Wagtail): it was perched on top of a hedge, then flew down into next door's garden; it was about the size of a Blackbird or slightly larger, with quite a long tail; its plumage was 'more striped than a Magpie', and the orange was 'underneath'.
If you took that description at face value, you would have to conclude that it wasn't anything on the British List, and possibly not even anything known to science. Now, the chances of my auntie finding something new to Britain in her garden are remote, and the chance of it being new to science is zero. So, unless it was an escaped cagebird, it was probably something common.
But what? Bill Oddie said in his Little Black Bird Book that "99 per cent of laymen's funny birds refer to Jays." That's always a possibility, but the Pied Wagtail bit makes me think it was more black and white than that, and I think I'm coming round to the view that Great Spotted Woodpecker is the most likely candidate.
All of which only goes to show just how hard bird identification really is, and how much most of us take it for granted that we can quickly and easily identify most of what we see.