having created my beautiful model and parented it to a skeleton I have spent many happy hours playing around with the positions of the bones to attempt to stop the mesh scrumpling in all the wrong places, with little success, any ideas of techniques to help would be mot appreciated 
Use this handsome technique to save your beautiful models ( it’s just the 1 456 653 time that 'ive very pleased to answer that question).
Unparent your nice model with keep transform Apply Ctrl-A to your
lovely modeland reparent!!
And the life it will be wonderfull!! 
Bye
António