Found on another website that he is 46 years old. Only been a league ref for a few years so late promotion seemingly.
Found some further information about Brook. He started refereeing at 14 and got on to the EFL at the age of 44 after 30 years working his way up through the ranks. A most commendable example of diligence, perseverance and not giving up. It's good to know, in these days of Development Groups and accelerated promotions, that there is still room at the table for a referee with such a steady progression who perhaps had a few setbacks along the way but never gave up on the ambition.