Derek Johnstone last night insisted he was "embarrassed" to be associated with Rangers after the club began the process to enter into administration.

The club have endured a trying season, but the situation reached a nadir as papers were lodged with the Court of Session.

It was all a far cry from the heady days enjoyed by Johnstone – who made over 350 appearances over two spells at the Ibrox club – which was punctuated by domestic success and victory in the European Cup Winners' Cup in 1972. A proud Rangers supporter, Johnstone is shaken by events at Ibrox.

"Yesterday was one of the worst days of my life. I have never been embarrassed to be a Rangers man, but yesterday I was," said the former Ibrox striker. "I have never been ashamed to be part of this club, never. Not when things have been poor on the park, not during any time of adversity. But what has happened at Rangers these past few months has been cringe-worthy.

"Ever since the news broke I have had a sickness in the pit of my stomach. Even now I cannot believe it. I know that there have been suggestions that this was coming, but I don't think anyone appreciated just how bad the situation was.

"We have all spoken about the possibility of the club going into administration and there have been rumblings about it all season, but I cannot believe how quickly it has happened. Like every other Rangers fan, I am shattered. It is frankly awful news. Right now, the league title does not matter one jot. What is at stake is the very existence of the club, its very fabric. It is gut-churning to think about the future and the struggles that lie ahead in simply ensuring the club actually stays alive. Yes, it is that serious."

Rangers also yesterday announced that Daniel Cousin had returned to the club until the end of the season. The signing was supposed to assuage some of the discontent felt by supporters after the sale of Nikica Jelavic on the final day of the transfer window, but instead it has left a bitter taste.

"That makes no sense whatsoever and only shows how much Ally McCoist [the Rangers manager] has been kept in the dark about what has really being going on at the club," said Johnstone. "Why sign up to spend £7500 a week on a player if you're going into administration? Like so many things under Craig Whyte's regime, it does not add up.

"Who could ever have thought a club like Rangers, one of the great institutions of the Scottish game, could end up in this sorry, dreadful mess. There are two men who need to stand up and take the blame – David Murray and Craig Whyte. The buck stops with both of them. [Murray] dug the hole, but as if that wasn't enough, he then sold Rangers down the river when he turned control of the club over to Whyte."

The culpability of Murray – who sold Rangers to Whyte last year – will have been debated by disillusioned supporters last night, but Johnstone was scathing in his assessment of the former chairman's stewardship. In particular, he criticised the decision to hand the club over to Whyte.

"What is particularly galling is the fact that every member of the Ibrox board warned him against the deal," he said. "They did not trust Whyte, they were suspicious of him from the start and they did not want the running of the club put into his hands. But Murray ignored those concerns and he has to be answerable for that.

"Where is the money from the sale of Nikica Jelavic? Where is the money that [Whyte] was putting into the club? He has not invested a single penny in Rangers since he took over. In the last 40 years I have known every Rangers director, every one. They have been proper gentlemen and they have been proper businessmen. John Lawrence would be turning in his grave. Craig Whyte might be a reasonably successful businessman, but he does not know football?

"I will watch with interest to see just what Sir David Murray has to say on the matter. He most certainly does not walk out of this debacle without taking a massive portion of the blame."