From reading the AAIB report I understand that the weather was below sensible limits for sending a student solo (See Birmingham’s actual weather and what the FI says when he flew to Welsbourne and the weather deteriorated about 1/2 way on route)
There was to much risk involved sending the student solo, so why did the instructor do it?
Don't give me this hindsight bullsh*t.
What the instructor should have done was fly back dual with the student or arranged other transport for him. Simple no discussion with other FIs or the guy who pay's your wages etc.
So carb icing caused the engine to stop but without a doubt bad weather compounded the problem and put the student under a lot of pressure add this to following another helicopter in formation the outcome of the flight comes as no surprise.