Seeing as the only registered Directors when the non-payment took place were MD and his Dad I think that's a bit unfair, the real money sits with MS (I am led to believe) and he has no legal responsibility.
I can't help thinking that any court action would just bring around the winding up of the original company as they now have established more companies.
If this is the case you will have to prove wrongful trading if you want to go for the directors personally.
Phil