Prepare for plenty of mentions of the "Cheltenham roar" up until lunchtime, the traditional crowd greeting that heralds the start of the biggest four days in National Hunt racing. You won't be able to gauge the number of throats precisely, one Cheltenham opening roar does pretty much sound like any other, but be assured there will be plenty of talk too about the numbers that come through the gates of Prestbury Park, today and throughout the week.