The Seven Barrows handler said on Saturday asking Simonsig to return in such a white-hot atmosphere might not be best for the horse in the long run, and that he would prefer to give him a racecourse gallop over the Festive period.
That course of action remains a possibility, but Henderson’s main aim is to get the unbeaten chaser to the Cheltenham Festival in March.
“He’s not going to Kempton,” said the trainer.
“We’ve got work to do with him and it’s not an overnight job.
“Like them all, he’s a high-profile horse and we’ve got to do what is right by him.
“He isn’t going to make the King George so there was no point pushing him any further.
“I would love to get a racecourse gallop into him and Sprinter Sacre somewhere over Christmas but the next two days will tell us an awful lot as they will school on Friday and work on Saturday.
The news Simonsig will miss the King George did not come as a shock to the race sponsors, with the grey’s defection causing minimal ripples in the ante-post market.
“We gradually pushed Simonsig out in price as the doubts increased over his participation,” said Hills spokesman Jon Ivan-Duke.
“A week ago we were 8-1 and he was 12-1 on scratching, but we would have loved to have seen him back in action.
“However, his absence only strengthens the case to be made for the market leaders, Silviniaco Conti and Champagne Fever, who are the two best-supported horses in the ante-post book.”
William Hill King George VI Chase
Sponsors bet: 5-2 Silviniaco Conti, 3-1 Champagne Fever, 7-1 Al Ferof, 8-1 Menorah, 9-1 Cue Card, 10-1 Dynaste, 20-1 Road To Riches, 25-1 bar.