This is the Brompton Oratory, South Kensington, London, just today:
So what's the problem? The sun. It's out. In early April. And when I took the photo about two hours ago, it was 20°C outside.
More early-April madness:
Just look, will you? Londoners eating lunch outside. Insanity!
The weather is so freakish that I've actually got a mild sunburn. A sunburn! In London! I don't even think they sell sunscreen in the UK. But I'm going to go have a look—just to make sure for myself that the weather really is this weird.