Hart was contemplating a season sat on the bench watching Shay Given at Manchester City until McLeish stepped in to take the keeper on a year-long loan at Birmingham.
The move paid off handsomely, both for the progressive St Andrew's outfit and Hart, whose outstanding performances throughout an impressive season saw him muscle his way into the group of three keepers named in Fabio Capello's 30-man provisional squad.
Barring some unforeseen disaster, Hart will be on his way to South Africa at the beginning of next month.
And the former Shrewsbury star accepts it is all due to a Scot.
"I owe a lot to Birmingham for giving me the opportunity to go and play there," Hart told the FA's official website.
"Options were limited at Manchester City and Alex McLeish gave me a big chance to go and show what I could do.
"Fabio Capello made it very clear that you had to be playing regularly to stand a chance of being involved with England, so what happened at Birmingham is 100% why I'm here."
It means Hart can look forward to being part of a World Cup rather than having to watch it on television.
His experience of the 2002 and 2006 tournaments leaves him knowing exactly what will be happening at home as Capello's men aim for glory.
"The whole country stands still," he said.
"The World Cup unites everyone. No matter who you support, even if you don't particularly like football, you can't help but get involved.
"You plan your week around it. You just get behind the team and want England to do well.
"That definitely helps and gives everyone around the team positive vibes."
More positive vibes would accompany news Gareth Barry is fit, but the City midfielder will not find out until tomorrow when his ankle injury is checked out.
Capello has already stated that if Barry is likely to be fit for the opening Group C game against the United States in Rustenburg, he will be part of his 23-man Three Lions party that is announced on June 1.
However, if recovery from an innocuous-looking incident during City's home defeat to Tottenham on May 5 takes any longer, Capello has a tricky decision to make before England return to their training camp in Irdning on Wednesday.
"Barry is one of the players we want to be fit," said Capello.
"If he is fit, he will come with us. If not, he will stay at home."