Have been hatching an idea for the safety catch. Those to whom I have spoke say the plans catch is fallible, and the plans say it is a difficult part to make, and pre-fabbed parts are no longer available. The safety catches on our new UPVC double glazed windows look brilliant, so I stole one from #1 son's bedroom and snuck it into the shed to experiment. I made a test piece from two bits of hinged hardwood and it all seems to work nicely. Hmmmmmm.
Plan is to place a 1/4" aluminium hardpoint in the canopy frame, and tap it to attach with AN525-10 screws. Will either use the flat plate on the longeron, or use a AN3 bolt through the longeron.