The club's chairman, Milan Mandaric, said that he wanted to take his time appointing a full-time manager following the dismissal of Jones.
"I didn't want to make a quick and aggressive decision," Mandaric told the club's official YouTube channel.
"I wanted to give us time and make sure it was the right decision. You can't just make a decision from one or two games. It paid off.
Mandaric went on to say that the performances since Gray took charge, as well as the results, proved that he deserved the role.
"The results are most important, but also the strategy of playing the game, scoring some goals, say that he is the right man," he said.
"The response of the players and everyone else around Stuart really showed that he is the right character of the job."