tanking off in the ring!!!

[TooManyColoureds]

i have a coloured that i plan to do some bspa workers with next year but we have issues with brakes at the moment !!!
at home he is a christian and can be ridden in anything without a problem but when we are out doing our ridden show with all the other horses and is asked to trot he either stuffs up and shuffles so you go to push him on and he sticks his head up and runs off then in canter he drops his inside sholder and tanks and i have no brakes whatso ever !
he is 12 years old and i have had him for 9 years and he is well schooled but we used to event which was fine as he was always on his own in the ring but now when his is put with other horses he thinks its one big coloured race !!
he is currently ridden in a rugby pelham as he found the double too much in his mouth.

any help would be appriciated

[sarah14]

try maybe a swales? my section d did this swales helped alot not for at home just in the ring,

[sarahp]

Lots of gentle riding in company, both hacking out in a gang or schooling in the arena - we used to get together and do mock show classes. I good exercise when hacking is to make him stand and wait while all the others go on (if you can!), and make them stand while yours goes on in front - this should get him used to going first or last.