I only watched a couple of episodes and then the final and thought that some of the challenges, particularly baking over an open fire outside on a day in the middle of the heatwave was ridiculous.
It's as if they are trying to think up more and more extreme challenges which are far removed from what I think Bake Off should be about.
I think Prue looks fabulous for her age and is full of fun and so much more personable than posh Mary was
Prue is fun, looks great but she is in fact much posher than Mary is! 
As for the jar shattering - I have known that happen with a thick tumbler which was sitting on my desk. It exploded with a loud bang, shattering into tiny pieces and startled everyone in our office - we didn't know if it was from heat (no heat source nearby) or vibration from traffic outside.
I couldn't help comparing the three showstoppers with the lovely creations made in the Wedding Cake challenge on BBC.