Life for Ferguson could have been so different had United's original knight of the realm wavered when the pressure started to be applied ahead of the famous FA Cup tie at Nottingham Forest in 1990. As it happened, Busby was solidly behind his fellow Scot, feelings that were portrayed to the United board by Charlton.
"Sometimes you would have a little chat about things but Matt was in no doubt either. He didn't have a worry at all. He knew we had the right man," said Charlton.
It is one of Ferguson's great joys that Busby, whose record as longest-serving United boss he will take on Sunday, was still alive and at Old Trafford to celebrate at the party that followed a day after that 26-year wait for the title had been brought to an end in 1993.
The elation on Busby's face when United took the field for the carnival night against Blackburn after Aston Villa had failed to overcome Oldham gave away his feelings.
After building a club around his own European odyssey, the tragedy of Munich and glory against Benfica in the 1968 European Cup final, Busby knew United had a worthy successor.
"That night was magic," recalled Charlton.
"The old man was so happy. He loved Alex as well. He couldn't help it.
"Alex had this personality. He made things happen. Every part of the club was buzzing."
Source: PA