the ANO refers, section IV, 17 1 (a)
"Notwithstanding that the flight is being made with air traffic control clearance it shall remain the duty of the commander of an aircraft to take all possible measures to ensure that his aircraft does not collide with any other aircraft."....
and perhaps it could be argued that if the commander is unable to receive some sort of control service (radar, procedural in CAS) whilst flying in cloud then "all possible measures" includes taking another route, altitude/Flight Level or even not embarking on the flight!
ShyTorque, I know exactly where you are coming from since I have often been there myself and when you are flying for a living we have to make a professional "risk assessment" of the situation at the time....but once the action of flying in cloud without any radar cover becomes a president then I think we all need to take a rain check as to what it's all about.
I am NOT saying I would NEVER fly in cloud without radar but when it becomes a regular habit then we are stacking up the odds for something rather unpleasant! Also, in the litigous type of world we know seem to live in it's giving the lawyers plenty of ammunition should anything go wrong.