Former Swansea City fullback arrived at Spurs over the weekend.
"Ben is a fantastic player and he'll do really well for Spurs," John told Wales Online. "We've shared a room on Wales trips and I know him well.
"He isn't much older than me, but he has shown over the last two or three years playing Premier League football for Swansea that he has real quality," he added.
"We were each given a chance by our clubs and were able to make an impact.
"Swansea are a very good footballing team and Ben's playing style suits that. It was easy to understand why a number of top clubs wanted to sign him."
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