snug and safe

I had to put back my plans to work on my improved rear light attachment system to fix this when I got home after it did another of its suddenly-loosening-and-flapping-enough-to-attack-the-spokes tricks. I had been using M4 bolts so that the orange tightening-wheels of the replacement hooks could still be used, though the rearward one was evidently much less secure as it required tightening a bit reasonably often and tightening a lot every now and then whilst the forward hook remained firm. After removing the previous arrangement (where the head of the bolt was behind the rail) I was casting around for a method of sticking the nut behind the rail without it slipping through when I noticed that the (intact) upper portion of a since-replaced broken click-fixing bracket for my seat pack was almost exactly the right size and shape to fit extremely snugly beneath the bowed-out section of the rail, whereupon it would then provide two reasonably solidly-held M5 nuts, one to attach the hook and another to hold the bracket to the rail and stop it twisting. It would be firmer (but less snug) after being lightly truncated and reversed but it'll do for now.