It is possible - there are no other sightings around that date in the London Birding Blog, but that could just mean that no other birder saw it. They are a bit hard to confuse with anything else!
"Let loose the Kraken!"
One should never say never as even scarce birds like Hoopoe can turn up in unexpected places especially during migration time. As Stuart says they are very distinctive birds.
I don't want to do your daughter a disservice but I suppose she couldn't have mistaken it for a Jay. Although the overall appearance is very different some of the colouration is similar
Here's Hoopoe with its long(ish) bill and distinctive crest
And this is a Jay. Much bulkier with a short thick bill but a similar salmon pink colour. She could certainly have seen one of these in a London park
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Tony
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My thanks to Stuart and TeeJay. My daughter says it definitely wasn't a jay. I actually believe in the hoopoe myself, but it's a pity no one else reported it, and I can quite understand the experts being sceptical.
Good for her for sticking to her guns. I'm certainly not going to say she didn't see one. All sorts of birds can drop in on passage in the most unexpected places. I'm quite envious as I've only ever seen them abroad and not in this country.
Very old post, but i can confirm a sighting of a hoopoe in london today. Very familiar with them, their flight and habits, one crossed the A3 heading north right in front of me, took a double take, couldn't believe my eyes.