Bates, who has died aged 73, joined the Whites as an apprentice and stayed until 1976, experiencing the club's most glorious era under Don Revie s management.
The Doncaster-born player had to work his way into Revie's squad the hard way, alongside Gray, as was the tradition in the 60s.
“Mick was my workmate when we first started at Leeds United, we were on the ground staff together, but we weren’t very good at it," said the Scot.
“Don Revie took me and Mick off the ground staff when we were 16, you were meant to stay on it until you were 17 and a professional, but he took me and Mick off beforehand, probably because we could play a bit as well and we trained with the first team."
Although Bates could, as Gray put it, 'play a bit' he was behind a pair of greats in the Leeds pecking order. Billy Bremner and Johnny Giles held down the midfield slots, although Bates did manage an impressive tally of 191 appearances for Leeds and claimed a piece of history by scoring the all-important away goal against Juventus in the 1971 Fairs Cup final.
He could quite easily have departed for more regular football elsewhere and Gray would not have blamed him, but Bates loved Leeds.
“He was a smashing lad, Mick, he was a top player, I always said he should have moved on as he was the understudy to Billy Bremner and Johnny Giles, but he loved the club so much and being part of it, which is why he stayed from 1963 until 1976," said Gray.
“Mick had a great rapport with all of his teammates and everybody in our squad liked him, he was a great lad. He was a terrific player and probably the highlight of his career was the goal he scored away at Juventus which won the club the Inter-Cities Fairs Cup on away goals in 1971."
Bates went on to have spells with Bradford City and his hometown club Doncaster Rovers before running his own insurance firm after retirement from the game.
He and Gray were among those present to see the Revie Boys bestowed with Freedom of the City by the council in 2019, as part of the club's centenary celebrations.