The striker was best known for his performances at Liverpool in the 1960s, followed by his hugely successful lunchtime television show, Saint and Greavsie, which he co-hosted with close friend and ex-player, Jimmy Greaves.
So, who was the Scottish player and what were some of his career highlights? This is what you need to know.
Who was Ian St John?
St John was born and raised in Motherwell with five siblings.
He showed sporting talent from a young age in both boxing and football, but his mother discouraged his pursuit of boxing and instead, he excelled on the pitch.
In 1957, aged 19, he signed as a professional player for his home team, Motherwell, while also working as an engineering apprentice.
He was managed by Bobby Ancell, and became known as one of the ‘Ancell Babes’ alongside other inspiring young players - Andy Weir, Willie Hunter, Pat Quinn, and Sammy Reid.
He married his wife, Betsy, when he was just twenty years old and the pair welcomed children and grandchildren together.
St John transferred to Liverpool FC in 1961, for a transfer fee of £37,500, (equivalent to £840,879 in today’s money).
This would be the beginning of a great football career, as a player, manager and pundit.
What are his career highlights?
St John was a hugely influential player in the Liverpool team managed by Bill Shankly.
Throughout the 1960s, the team rose from the second division to win two English league titles and an FA Cup in 1965 -St John would score the winning goal in the final.
He left Liverpool in August 1971, after playing 425 games and scoring 118 goals for the club.
Alongside his success at Anfield, he made 21 international appearances for Scotland, scoring nine goals.
St John then went on to manage his former club Motherwell, from 1973 to 1974, and Portsmouth, from 1974 to 1977. He was assisted at Portsmouth by former Motherwell teammate, Willie Hunter.
His greatest achievement off the pitch came when he struck up a presenting deal with ITV for the football topical show, Saint and Greavsie, alongside friend and Tottenham Hotspur legend, Jimmy Greaves.
The pair hosted their lunchtime show from 1985 to 1992, with Greaves’ son Danny describing his father’s time on the show as “two friends who came together, two ex-football colleagues, ex-players, who understood the game and just generally had fun and a laugh.
He added: “It wasn’t work for them. They turned up on a Saturday afternoon to talk about the game they both loved and fell about laughing for a couple of hours. That’s the underlying memory.
“The great thing about Saint and Greavsie was that a lot of people who didn’t necessarily follow football got into it because of the show. The show almost became more important to watch than some of the games.”
St John is still considered one of the greatest players of Liverpool F.C. by fans.
How have other football players paid tribute to him?
St John passed away at his home on 1 March 2021.
He had undergone surgery for bladder cancer in 2014, although it is not known if this was linked to his passing.
Leading the tributes to St John, Jimmy Greaves said: "I loved my time with the Saint making Saint and Greavsie. After my illness Ian phoned several times to see how I was.
“And now he's gone. He was a lot of fun to be with and a great footballer. He will be sadly missed. I will never forget his laughter for all the years we worked together."
He added on Twitter: “He was a lovely man and will be sadly missed by many many people. We must also remember he was a great footballer for Bill Shankly's Liverpool and beyond.”
Motherwell FC released a statement saying: "We are deeply saddened by the passing of Ian St John. The thoughts of everyone are with his family at this difficult time."
Liverpool’s current manager, Jürgen Klopp said: "He was not only football-wise a legend, but a true legend as a person. It was a pure pleasure to meet him."
Klopp continued: “I feel really honoured to have met him and when I heard the news today, I was devastated. All my prayers go to his family and I know he is in a better place as well.
“I am really, really happy I had the opportunity to meet him.”
Footballing legend Kenny Dalglish released a statement, describing St John as an “'icon”.
He added: “I send my prayers to Betsy, his wife, and the family and I just hope they are coping as well as they possibly can.
“He certainly was, and deservedly so, an iconic figure in and around Liverpool Football Club because he came in at the very beginning with Shanks and big Yatesey [Ron Yeats].”
The Scottish FA also wrote: 'We are saddened by the passing of former Scotland National Team international Ian St John.
“Ian won 21 caps for his country, scoring nine times during a career that saw him represent Motherwell FC and Liverpool FC.
“The thoughts of everyone at the Scottish FA are with Ian's family and friends.”