Nicky Henderson finally admitted defeat in his race to get Constitution Hill to the Cheltenham Festival on Monday after further blood tests indicated his star performer had not recovered sufficiently from the respiratory infection discovered last week.

Here, we look at a timeline of how the events unfolded:

February 27: Reports of Constitution Hill being eased down during a racecourse gallop at Kempton began to surface and bookmakers were quick to suspend betting on the Champion Hurdle.

February 27: Henderson quickly admitted the poor workout came “as a bit of a shock” and that Constitution Hill had subsequently scoped badly, but insisted he would not give up hope of making it to Cheltenham.

“Unfortunately, in a routine gallop this morning, Constitution Hill was very disappointing and it transpires, after the vet has scoped him, that there is evidence of mucus,” said the Seven Barrows handler.

“We’re taking a sample of it to a laboratory to analyse it, which will tell us about the significance of it and we should know more after that.”

February 27: Henderson then elaborated on the dramatic morning of events and initial medical tests.

He posted on X: “The sample from his tracheal wash has shown a small increase in the number of neutrophils which indicates a respiratory infection, which is significant but far from drastic.

“He will start a course of antibiotics immediately and we plan to rescope him on Friday in order to monitor which way this is going. He would only be having light exercise this week following this morning’s racecourse gallop.

“Both our own vet and the racecourse veterinary surgeon who scoped him feel we definitely have a chance of correcting this in time and we will be doing everything possible to do so. We have a fortnight to work him and it is possible, so we will keep everybody notified accordingly.

“He is absolutely fine within himself and we have simply got to get on top of this issue as quickly as possible.”

February 28: Henderson issued an upbeat bulletin, stating on X: “I am pleased to say that Constitution Hill appears perfectly normal this morning. He is bright and well and ate everything last night. His temperature has remained normal both last night and this morning.

“As with all the other horses that galloped at Kempton yesterday, they are having an easy day today. They have had a lead out and all appear to be sound and well and are having a good pick of grass.”

He added: “Fresh air is as important as anything for a horse’s lungs. The intention is to rescope on Friday to monitor which way this is going.”

February 29: In a morning interview at Seven Barrows, Henderson described his superstar as “alert and bright”, as he walked a line between giving the gelding adequate recovery time, while trying not to lose too much of his fitness edge.

“He can’t stay in his box, if we’ve got any pretentions of running in the Champion Hurdle, you can’t just knock it off and tuck him in bed,” Henderson told Sky Sports Racing.

“We’ve got to find the right balance between keeping him moving but not stressing him in any way at all.”

February 29: Henderson later received the results of a blood test on Constitution Hill and admitted they were “probably not what we were hoping for”.

In an update posted on X, he said: “The result of the blood test taken this morning goes quite a long way to explaining his disappointing performance at Kempton on Tuesday and confirms that he has a significant degree of inflammation.

“The figures themselves suggest he is definitely under the weather and we will need to repeat the test again on Monday in the hope that the situation improves.

“This is probably not what we were hoping for, but at least it tells us exactly where we are.”

March 1: Some positive news among the gloom, as Henderson says: “On what was about as foul and filthy morning as you can imagine at Seven Barrows, Constitution Hill had a light exercise and was rescoped afterwards as planned. This showed the neutrophil percentage, indicative of infection, was back to normal parameters with no mucus evident.

“This is obviously positive news but we cannot hide behind yesterday’s blood test which basically reveals that, in simple terms, our horse is ‘unwell’.”

March 2: Henderson was on a rare visit to Kelso, where speaking about Constitution Hill he affirmed: “The blood test on Monday will tell us everything and we will know where we are after that.

“If we don’t get the results we want on Monday, I wouldn’t go as far as to say it will be the end of the season. Let’s just cross each bridge when we come across it.

“When you train horses, you are going to walk into these situations and you’ve got to face up to it.”

March 4: The eagerly-awaited blood test results confirmed Henderson’s worst fears, with a title defence ruled out for Constitution Hill.

Henderson posted on X: “Very sadly we are going to have to admit defeat in the battle to get Constitution Hill ready for the Champion Hurdle and therefore have to declare that he will not be running there this year.

“He has undoubtedly improved over the weekend and seems noticeably brighter than he was at the end of last week and I really did think he was much perkier when ridden this morning.

“Unfortunately, the all-important blood test shows that although the figures have also improved, they are quite a way from being satisfactory for a horse to commence serious training and to race in a week’s time.

“This is very sad for all of us and particularly Michael (Buckley, owner) but it is in everybody’s best interests that we ensure we have a fit and healthy Constitution Hill to win back his crown next year.”