A new roof on the shed!!
It's only been a year (or more) since it started falling in. But no more; the new roof is on today.
Looking back, I can see that the old roof was a poor thing. I followed conventional (aka cheap) practice of using chipboard covered by shed felt. Chipboard, when wet, has all the strength of cold porridge and it's heavy too. Shed felt is horrible stuff to work with and when it inevitably fails it lets water into the chipboard which....well, don't stand underneath it is my advice.
So, judicious application of a wrecking bar removed it in much less time than it took to install it. Two new "joists". Then a combination of an underlayer of builders damp-proof membrane on the top and bottom thirds of the roof and the whole overlaid with clear corrugated PVC sheets which, handily, come in just the right size! So the roof is waterproof and the shed has lots of light because the middle third of the roof is transparent. Neat, or what?
And finally, in a burst of mad enthusiasm, I painted it too. No, not the roof! Just the walls, and it looks a damn sight better for it.