Rooster Booster - died on Tuesday morning.
Rooster Booster died on the gallops this morning while being prepared for the Stan James Christmas Hurdle at Sandown on Boxing Day.
"He died of either a haemorrhage or a heart attack. We're not sure yet," said trainer Philip Hobbs.
The 11-year-old grey won the 2003 Champion Hurdle and was runner-up to Hardy Eustace the following year.