Help please re clutch slave cylinder

I had a difficult breakdown today - in heavy stop start traffic the clutch on my TE21 suddenly stopped engaging. After towing it home and inspecting from underneath I could see that the slave cylinder piston had been pushed out of the cylinder and was trapped at an angle across the end of the cylinder thereby preventing the clutch from releasing.
Perhaps the linkage was badly adjusted and allowed too much travel when the pedal was fully depressed?  My question relates to the connection between the slave piston and the pedal linkage. It is held by a bolt which may be threaded into the fork - the end is certainly threaded. Should it have a nut?  If so, what is to stop the nut from unscrewing? There is not enough length for a split pin.
I should be grateful for any experience you can offer!

I suspect the slave piston has come out of the slave cylinder because the internal clutch thrust ring has worn to nothing allowing the slave piston to travel too far.. The likely difficult solution is to remove the gearbox and replace the worn carbon ring and probably the the clutch plate and cover plate while you are at it. The threaded bolt has neither split pin nor nut ,it is simply screwed in to the forked operating arm tight. You may be lucky and get away with simply removing the the slave cylinder and refurbing it or replacing the ,worth trying before tearing the box out
Good Luck

Hi Peter. Thanks for your help. This is not what I wanted to hear but your analysis makes sense.
Regards

I managed to get the car onto a lift so that I could inspect it more carefully.
The short rod between the slave cylinder piston and the clutch operating arm was banana shaped. I hammered it straight and put everything back together and all now seems to be well.
I assume that once the rod had slipped out, the hydraulics were strong enough to bend it?
If it fails again the gearbox will have to come out. I shall let you know. Thanks. Mike

Just to close out this thread - thank you to those who offered advice.
I have not had any further clutch problems so the cause of the bent clutch operating arm is still a bit of a mystery.
Mike