WHY 'given the office'

Deputy

horses respond to the jockey's actions, they don't know if they are off or not on the day until.......

give (one) the office
obsolete slang To give one secret, private, or insider information or news.

They also saw a horse has been given a peach

In the van. Transit, presumably.

Ice cream

in the catbird seat

Why Idioms?

Interesting topic. Culturally diverse.
Old as time cuz.

They are ten a penny.

In the van is short for vanguard which they say when a horse is up the front
"a group of people leading the way in new developments or ideas",think it has an army meaning about forward troops.

I know what it is meant to mean - but can't understand the derivation! I think the commentator is saying the jock is now riding the finish, urging maximally but i don't see anything 'secretive' or 'private' about it!! Or what a 'deputy' or 'ice cream' have to do with anything!!  And 'catbird seat' - wtf - where's that??!
Thanks for the comments tho!

As punchestown says, in the van means up the front, from vanguard.

You sometimes here the humorous inverse, in the guard's van, meaning at the back, because the guard's van is (or was) at the back of a train.

The catbird seat made its way across the Atlantic from American commentaries. I can't remember if it was Cash Asmussen or the Breeders Cup which led to its overuse here for a few years. It meant near the front with seemingly plenty in hand, from what I recall. Where the Americans got it from, who knows?

mrcombustible's given a peach is just a shortened form of a peach of a ride, where "a peach of" is an old-fashioned way of saying top quality.

I'm not sure I've heard ice cream but would imagine it is a variant of cool, like sitting chilly.