So I opened one of the tents to find the light wasn't on! Checked the timer, ok! Gave the power cord a wiggle and could hear arcing at the T connector!
I took it apart and checked for a loose connection, everything was tightish!
I then removed the wires and found the ends were covered in solder, which they shouldn't by with this type of connection! And the wire had been pushed too far in so the screw was going through the insulation and making contact with the wire there which has led to it overheating and becoming brittle eventually leading to it failing!
This was on both the live and neutral main supply wires!