What is this?
Testing of Christmas lights in a walkway under a busy intersection?
Underground sewage workers brightening up their tunnels with coloured fairy lights?
The new user-friendly tube stations, flashing coloured lights as you approach a station?
I look forward to reading your best guesses!
The Answer will be posted in a day or two, because if I put it on here, WP will show it to you in the Reader in a mini photo, and you won’t have to guess at all!
And where’s the fun in that?