Having previously broken the clamps it was inevitable that the bolt would be next. It went 'crack' over some bumps at about 40kmh. Clearly something has broken, I thought.
The saddle fell off as I battled to keep straight and slowly brake around a curving road through the Davo swamp. The bolt and the clamps landed and bounced on the road as I continued onward another 20-30m so so. They were a bit hard to find but I got the important bits.
Luckily the saddle was tied by its rails to the post with a tyre-sock or I would have been searching the roadside for it, too. I sat it on the post for the slow, mostly-out-of-the-saddle trip home. (Once before I had done this on a Gitane and rode over 30km back home, out of the saddle.)
Could have been worse.