Snaffles- allowed in top level showing?

[show.pony]

Are snaffles allowed/widely used in top level showing? Been told by some people that its not actually allowed and looking through pictures of HOYS ponies haven't seen any wearing them!

 

[be positive]

Snaffles are allowed but most will be ridden in a double or pelham as that is considered correct and at top level the horses should be going well enough to be happy in a double, workers are more commonly shown in various types of snaffle than those in flat classes.