CELTIC were enjoying themselves so much they didn't want the beginning to end.

When fourth official Brian Colvin held up his board showing there would be only two minutes of stoppage time at the end of the 90 there was a ripple of mock booing from the enormous away support. They wanted longer. A day of unbridled pleasure had delivered a rout and the outcome they had been longing for for weeks . . . in fact, years.

Their biggest win of the season merely removed a doubt which never actually existed – effectively they became champions the day Rangers had 10 points struck off for going into administration – but confirmation was validation for Neil Lennon and a young, promising set of players who feel like they are at the start of something. "This is only the beginning" was a theme from Celtic on the day they took the league championship back for the first time in four years.

Tempting fate is unwise in football, it has a habit of humbling those guilty of presumption, but it was easy to understand Celtic's breezy view of the future. The club is on a solid financial footing, it has a squad rippling with potential and a young, ambitious manager. Just as significant is the likely weakness of the challenge from Rangers over, at least, the next two or three years. Whether they are owned from Scotland, the United States or Singapore, Rangers will be starting from scratch. There is no suggestion they will have more money to rebuild a squad than Celtic will have to tinker with their own.

As much as many Rangers supporters might like it to be otherwise, their club's guilt and embarrassment is non-transferable. Some will continue to snipe that Celtic's is a "tainted title" but the insult is easily dismissed. It is a time-honoured practice for one set of supporters to try to belittle and cheapen any achievement by their rivals but all it took was a look at the face of everyone connected with Celtic to see what this result meant to them.

What's generally missed about the "tainted title" jibe is that it would mean something only if Celtic themselves felt that their achievement had been in any way lessened or tarnished. They feel no such thing, and nor should they. They look at 21 consecutive league games unbeaten, and 17 straight wins, and they see that the strongest team in the country wears green-and-white. They would have a handsome lead and be closing in on the title even if Rangers' hadn't been punished for trying to buy and pay players they couldn't afford without paying their taxes.

There was a symmetry in Celtic wrapping up the league at the ground where almost everything was lost, although it's simplistic to point to the famous 3-3 draw in October 15 as the only catalyst. They were only 10 points behind Rangers after that result and the gap soon grew to 15. They were jeered at Parkhead after a 0-0 against Hibernian a fortnight after the Kilmarnock draw, and when they went a goal down in their next league game, at Motherwell, they were flirting with crisis. Coming back to win at Fir Park was just as significant as the 3-3. "After that we never looked back," said Lennon.

They ate into Rangers' lead so quickly they overtook them at the top by winning the Old Firm game on December 28. Crucial victories followed at Tannadice and Tynecastle as they built the spine of a championship win.

Charlie Mulgrew's signature is all over their campaign and he had the ball in the net twice, and crossed for Glenn Loovens and Gary Hooper to score too, before half-time on Saturday. Their second half was so relaxed it could have been set to music. Actually it was. While Joe Ledley and Hooper scored again fans amused themselves with paeans to heroes old and new. Tommy Burns, Jimmy Johnstone, Henrik Larsson, Jock Stein, Shunsuke Nakamura, Lennon, his backroom team, Craig Whyte . . . each of them got a song or two to himself.

The day was a complete and utter humiliation for Kilmarnock on and off the park. They may have acted as good sports (and cashed in) by giving Celtic nearly 13,000 tickets to swell the attendance to 15,926 but the total occupation of their ground was emasculating. Moving their own season-ticket holders from their preferred seats so that Celtic fans could have them was one thing, but for the club to allow celebratory songs and interviews to be done over the public address system afterwards was too much. There is a point where a host club being hospitable can cross into surrendering dignity. Kilmarnock were more like event organisers than opponents.

For Celtic the Scottish Cup and a potential double awaits once their heads clear from the initial partying. A loss of competitive edge in their five remaining league games would be understandable but they will want a final winning margin of more than 10 points, if only to remove the argument that an unpunished Rangers would have won the league themselves.

If Rangers win at Parkhead in 20 days' time it will their third victory in four derbies. It will not matter much. Any attempt to disparage Celtic's position as the deserving champions is a lost cause.