But, the 73-year-old who has served the club as a player, assistant manager and now kit controller, is honest enough to accept the chances of his beloved Hoops ever retracing their path to a European final are receding by the year.
The appearance in Saturday's final of Atletico Madrid should give the smaller clubs hope. But, while their opponents in Lisbon, Real Madrid, and the other super powers continue to get richer by regularly reaching the final stages of Europe's premier competition, the gulf between them and clubs like Celtic will grow only wider.
Asked if he could envisage Celtic contesting for Europe's premier prize again, Clark replied: "I can't see it happening.
"Barcelona, Real Madrid, Bayern and PSG - the cash they all have is amazing. It'll be really difficult to win a European Cup again.
"The way finance is in Scottish football, we're up against it. Reaching the last 16 is an achievement.
"It's all changed. An achievement to Arsene Wenger at Arsenal is the top four (in the Premier League). Any other era that sort of talk from an Arsenal manager would not be tolerated."
Clark sees first hand how tough it is just to reach the group stage from the starting point now allotted to Celtic, and reflected: "We played Zurich, Nantes, Vojvodina and Dukla Prague to get to the final.
"These days, you have to play more than that to get to the group stages.
"It's all about the finances of football now.
"You just have to see that Derby County could earn £110million from the promotion play-off and are splitting £4.5m among the players.
"It's a different world now. But, good for them."
There is no bitterness in this modest man who is content to pick up the dirty kit of players who will never achieve a fraction of what he did during his career.
The highlight was, of course, the 1967 European Cup final win over Inter Milan, and the memories are as sharp as his wit as he prepares to join his former team-mates for the nostalgic journey.
They will raise at least one glass to departed colleagues - Jimmy Johnstone, Ronnie Simpson, Bobby Murdoch and Jock Stein.
Soon, Clark will be back in the day job. But, do the current players realise they are in the presence of a club legend?
"Well, I don't go about telling them," is his pithy response. "But I think the players spread the word. They will come up and ask if it's true.
"If they are down in my room, I just show them the photograph and say, 'Take a look at that. The thing in the middle with the big handles is what you'll always want to win. I won it'."