IT is over half a century now since legendary Rangers manager Bill Struth passed away.

Yet, the mark he left on the Ibrox club has endured to this very day.

As the Glasgow institution has lurched from one crisis to another in the last few years, his name has often been raised.

"What would Bill Struth have made of this?" Gers supporters have asked as the latest bombshell about their troubled club has emerged.

So, just what is it that makes the man who was in charge of the Rangers team from 1920 to 1954 so special?

Why does his legacy endure all these years later?

That is what David Mason, the official club historian, and Ian Stewart, a lifelong fan, set out to discover when writing in their new book Mr Struth: The Boss.

The result is a fascinating insight into the life and career of one of the most influential figures in the 141-year history of Rangers.

Mason first got the idea to produce a biography of Struth when he wrote Rangers: The Managers, and interviewed his secretary Alice Dallas in 2000.

"She provided me with a lot of information and pictures," he recalled.

"It was an important thing for her that he should be recogonised by the club. It became her raison d'etre.

"With the help of Sir David Murray, we managed to get a bust of him commissioned and the main stand named after him."

Mason continued: "I have been fortunate in my time at Rangers of having access to lots of older players who go back to his day.

"I was always keen to speak to guys like Jock Shaw, Willie Waddell, Willie Woodburn and Bob McPhail, and find out about the history and past of Rangers.

"Something that really came through from speaking to them was how important Bill Struth was in terms of influencing their career.

"His influence in the history of the football club also really came through. When you are in the stadium, in the main stand especially, his ghost comes out of the walls at every turn.

"Take the manager's office, for instance. He created it in 1928 and worked there right up until 1954."

The standards Struth strived to attain and the success he enjoyed - he is, with 73 trophies to his name, the most decorated manager in British football - perhaps explain why he is so revered even now.

"Rangers was already very successful when Bill Struth took over as manager," stated Mason. "It had already established itself as one of the great clubs in football.

"William Wilton, the first Rangers manager, was a huge influence on the club. But Bill Struth probably helped to take it to another level.

"When he took over he started to put his own mark on things in terms of discipline and standards. He demanded quality. His maxim was: only the best is good enough for Rangers.

"Whenever the club is going through times of trouble, as it has been recently, he is always held up as the benchmark.

"People will say: 'Bill Struth would not have stood for that!' Or they will say: 'Bill Struth would be turning in his grave if he could see this'!"

Much is known about Struth's achievements as Rangers manager. He was, for example, the first boss to lead the team to both a double in 1928 and a treble in 1949.

But Mr Struth: The Boss also sheds light on his early years, his upbringing, his brief military service and his successes as an athlete.

Mason remarked: "We knew a lot of things in the football sense. Anything we picked up on relating to football when we were researching the book reinforced what we knew already.

"What we found most interesting was when we got into his ancestry and background. We unearthed a lot of things which had never come to light."

He went on: "We lucked out with a lot of our searches. We found out about his time in the army in the 1890s. I found out about 80 or 90 races that he took part in.

"Those were races in which he finished in the first three. He generally ran middle distances He also did the hop, skip and the jump. He did play football, but not at any great level."

That, though, was no hindrance to him becoming Rangers manager in what was an altogether more innocent era in the beautiful game.

Mason said: "Tactics didn't come into it at that time with managers. He picked the team and then left the players to get on with it.

"His strengths probably came in two areas. He could recognise a decent player. But I think his biggest ability was man-management.

"Just about everybody we spoke to had the utmost respect for him and regarded him as a father figure. He was strict. He set standards.

"The players who came to the club were told what the standards were and if he saw them deviate from them - if their dress was slovenly, if he heard them using bad language - they found out about it.

"He had a firm word in their ear. I think he expected them to respect their positions as Rangers players. He ruled with an iron fist inside a velvet glove."

Mr Struth: The Boss by David Mason and Ian Stewart is published by hachette UK and costs £20.