The Reuben Brothers are the junior partner to the Saudi Public Investment Fund at Newcastle United, but they still exert considerable influence. After purchasing a chunk of Amanda Staveley and Mehrdad Ghodoussi’s Newcastle shares following their exit from the boardroom last month, the Reuben Brothers now control 15 per cent of the club. And while their wealth pales in comparison toPIF‘s – as does nearly every private company in the world – the Reuben Brothers’ net worth is still an enormous £25bn. On paper, that makes them the second-richest owners in the Premier League, behind only PIF. Of co…