Meet Giants Hall of Famer Ray Flaherty, who last wore No. 1 before Malik Nabers

By deciding to unretire Hall of Famer Ray Flaherty’s historic jersey No. 1 for use by rookie Malik Nabers, the Giants have renewed focus on one of the franchise’s first great players.

The decision, which Flaherty’s family has blessed and which was reported exclusively by The Post, makes available the first number ever made off-limits by an NFL team.

“It’s a nice story because it will maybe remind people why No.1 was retired in the first place and they’ll learn a little bit about Ray Flaherty,” John Mara told The Post’s Steve Serby. “It’s a nice story for us to be able to educate people about who he was.”

An end, Flaherty played six seasons for the Giants, starting in 1929, after two seasons with the short-lived football New York Yankees, and with a one-year break to coach the Gonzaga basketball team in 1930.

In 1932, Flaherty led the NFL in receptions with 21 for 350 yards.

He also led the league in receiving touchdowns, yards per reception and yards per game that season.

Flaherty won his first NFL championship — he would later win two as a coach — in 1934 when he helped lead the Giants over the Chicago Bears, 30-13, in “The Sneakers Game.”

To better negotiate the frozen Polo Grounds field, Flaherty suggested the team switch to sneakers at halftime.

The move helped erase a 10-3 Bears lead and allowed the Giants to score 27 fourth-quarter points in the NFL championship game.

Coincidentally Wellington Mara had been in the stands for that game as an 18-year-old and John Mara recalled that it was something his father had told him about in the past.

Jim Barber noted Flaherty’s role that day while introducing him at his Hall of Fame induction ceremony in 1976.

“It was Ray’s idea to put the Giants in tennis sneakers and they came out in the second half and got up … [and won] the championship,” Barber said. “Since that day, some type of tennis shoe has been standard equipment with all Pro Football teams.”

The Giants retired Flaherty’s No. 1 following the 1935 season, marking the first time an NFL team had bestowed such an honor.

Flaherty, who began playing pro football for the Los Angeles Wildcats of the original American Football League, took over the head coaching job for the Boston Redskins in 1936 and remained with the franchise after the move to Washington in 1937.

During his time as head coach through 1942, he won two league titles and four division titles.

Flaherty also owns the distinction of being the inventor of the screen pass and the two-platoon substitution system.

Flaherty died in 1994.