Never leave a brooks saddle on your bike in Hackney - the tea leaves there know about bikes. And they will nick it. Especially during the flower market day.
The saddle was getting super comfortable (B66S) and I loved the sound the springs made. Got a replacement for now (a £6 pound seat) and will have to find out if my insurance covers a saddle being stolen. If so I will either have to take it with me whenever I leave the bike, save it for special occasions or perhaps invest in some fancy bolts.
I must say it's quite upsetting that you can't have anything of quality on your bike unless its welded to it.