Constitution Hill sent shockwaves through the Unibet Champion Hurdle market on Tuesday morning, with the participation of the reigning champion in doubt following a below-par workout in a pre-Cheltenham visit to Kempton Park.

As has become tradition, Nicky Henderson took several of his Festival contenders for a spin at the Sunbury circuit, including the unbeaten Constitution Hill, whose only start this season was in the Christmas Hurdle at Kempton on Boxing Day.

Bookmakers were quick to suspend betting in the wake of the work, and the Seven Barrows trainer told the PA news agency his superstar had since scoped badly.

“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 Henderson.

“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.

“Last week, he worked brilliantly and he was scoped 10 days ago, but these things happen, just like it did with him earlier in the year (having to miss Cheltenham on Trials day in January).

“Horses are like humans, look how many people had the awful cough around Christmas that took ages to get rid of.”

He went on: “The vets still think it could clear up in a week and all his serious work has been done already, whether he makes it (to Cheltenham) will depend on the severity of it.

“He was disappointing this morning working with Sir Gino (Triumph Hurdle favourite), who he has worked with in the past. He would normally go easily with him, but this morning he couldn’t, so Nico (de Boinville) realised all was not well and wasn’t hard on him.

“Obviously, the mucus was affecting him. He’s not coughing, he’s just got a dirty picture, as we say.

“I’m not saying definitely either way (about Cheltenham) and I’ll keep hoping. As you can imagine, it has come as a bit of a shock.”

Coral were one of the bookmakers to take down their big-race odds, with spokesperson David Stevens stating: “Having heard the reports that Constitution Hill hadn’t impressed in his work at Kempton, and seeing the market react accordingly, with him being such an important and short-priced favourite for his Cheltenham race, we took the easy decision to suspend the Champion Hurdle betting.”