Former Bayern Munich boss Jupp Heynckes has ruled out a return to coaching at Barcelona following Tito Vilanova's resignation.
Heynckes led Bayern to an historic treble last term before making way for Pep Guardiola.
Immediately after the season ended he revealed his intention to take a year off, although he never officially declared his retirement.
Given his Champions League triumph as coach of Real Madrid and his proficiency in Spanish, not to mention his success last season, the 68-year-old had emerged as one of the frontrunners to take over at Barca, with Vilanova forced to step down to continue his treatment for cancer.
However, he told Germany's Sky Sport News that he is enjoying his time away from the game.
"I'm keeping myself busy with hobbies and sport. I have my animals and a huge garden," he said.
"I think it would be impossible for me, after working at Bayern Munich, now to take over a new club.
"I have understood the signals my body has been giving me and I am feeling good, enjoying the time I have for myself."
The 54-year-old former Wimbledon striker played under Kinnear during their time together at the Dons and remains a close ally of the Irishman.
Sunderland-born Harford had a brief spell with the Magpies as a player from August 1981 to March 1982 having launched his career at Lincoln, and went on to play for Bristol City, Birmingham, Luton, Derby, Chelsea, the Black Cats, Coventry and Wimbledon, forging a reputation as a no-nonsense frontman.
He began his coaching career at Wimbledon before following Kinnear to Luton and then Nottingham Forest, and later became a manager in his own right at Rotherham, Luton and QPR.
Harford's 13 months as assistant to Karl Robinson at MK Dons came to an end in June, and it was later announced he was to take up a coaching role at Millwall.
Should he be appointed to assist Kinnear, the move would do little to ease the tension at St James' which was created when Kinnear was parachuted in above manager Alan Pardew by owner Mike Ashley.
The 66-year-old Irishman's arrival was greeted with both anger and astonishment as he was put in charge of all football-related matters, but particularly the club's transfer affairs.
To date, not a single senior player has been added to the squad, while Steve Harper, Danny Simpson and James Perch have been allowed to leave, although Harper and Simpson were always moving on anyway.
Pardew's priority is to recruit two proven strikers with Aston Villa's Darren Bent high on his list, although the ongoing stalemate over Papiss Cisse's refusal to wear the logo of sponsor Wonga on his shirt remains a serious complication.