Newcastle goalkeeper coach Paul Barron worked with James at Aston Villa and he has told Harper and Shay Given that the veteran England keeper's standards have kept him in the top flight.
Harper said: "Paul talks about how thorough he is and the application and thoroughness of his training. He is 37 but looking at him, he is now reaping the rewards of all that hard work in training.
"For last few seasons, he has rightfully deserved to be back as England's No.1. He has been outstanding.
"You see plenty of people who have the ability but do not put the work in and they fall by the wayside whereas with the people who may be don't have so much ability but put the graft in, they get their opportunity.
"It comes down the player at the end of the day. Paul Barron is a good coach and has worked with some very good goalkeepers.
"David James is a role model, playing for England at 37 and playing in the Premier League for 16 years.
"I will guarantee he will be in the PFA team of the year and rightfully so."