"Jonathan is a very experienced big race rider so we are happy to have him on and I think he has a huge chance of winning it for us," says James.
"This horse has had a very interrupted preparation but the way he ran through the line on Saturday he is exactly where he needs to be.
"We labelled him our future Derby horse as a pre-Christmas two-year-old and it has taken a lot of patience to get him here because he was quite immature but he has come to it at the right time."
Riddell became available for the ride after Field Of Gold was made an unlikely Derby runner so his regular jockey, Michael McNab, changed to stablemate Tutukaka, whose trainer Tony Pike he does much of the riding for.
Pike's other regular rider Leith Innes was already committed to Marchand while Sam Weatherley, who was in the mix for the ride on both Derby favourites, elected to stick with his family-trained horse Ess Vee Are.
So while the Derby riders picture is clearer after the wild 24 hours that would have kept sponsors Vodafone busy with the calls between trainers and jockeys, the major player still not confirmed is one-time favourite The Perfect Pink.
She was below her best when sixth in the Avondale Guineas leaving trainer Jamie Richards doubting the Derby on March 5 is the best target for her so don't be surprised to see her change tack and head for the New Zealand Oaks.
Two other early Derby favourites in Shamus, who goes to the Levin Classic because he is better suited by that 1600m and Auckland Guineas winner Dark Destroyer, who missed crucial lead up races because of a slight setback, will also miss the Derby.
So the great race has had its most dramatic build-up in years and we still have 12 more days to go.
What: New Zealand's premier thoroughbred race.
Where: Ellerslie
When: March 5.
Who: The elite three-year-old gallopers.
Distance: 2400m
Dollars: $1million, sponsored by Vodafone.