49.9% gives him the biggest share but stops him being able to do whatever he wants unchallenged. If he is a maniac then the current shareholders could stop him, if he is a genius then everyone lets him get on with it. At 49.9% it gives him enough of an incentive to get involved as any value he adds directly increases the value of his shares.
Is it fair to say Bill Kenwright has done a very careful deal to protect the club?
Time will tell I guess, but I cannot see someone investing £100 million (which is what I guess he would have paid to buy around 50%) and not look to get to the business of driving the club forward.