Most bizarre. Over the weekend I had 2 slow punctures occur. No recent off roading and the tyres looked fine with no evident punctures.
Ironically, my recently replaced Arnott Gen III airbags were also loosing air and on inspection of the manual valves I installed I realised the schrader valves had become untightened. After tightening up, no loss of air.
Looked at the wheels, tried to tighten the inner Schrader valve and the whole valve 'popped' out of the rubber tube - it had completely perished. Never seen anything like it.
Easy fix, but very pleased that it's nothing Range Rover (I'm sick of having to defend the marque)