Billionaire Kerry Stokes and his Seven Group entity have 800 million reasons for wanting a seat at the table as building products group Boral prepares for what looms as its biggest corporate shake-up in two decades.

Seven Group Holdings is already $150 million ahead on its Boral investment after first buying into the ailing company in March. All up it has invested $652 million and holds a 16.3 per cent stake worth around $800 million at the current share price of $4.