Back from a staccato training sabbatical he has concentrated his efforts on his stable stars today, horses like defending Cup champion Self Assured and new buzz pacer Franco Indie in the $170,000 Sires' Stakes.
A concentrated Purdon is a scary beast, Richie McCaw-like in his determination to collect shiny trophies not for their value but his.
It is easy to assume with the favourite today much of Purdon's work is done but Self Assured is swimming against the tide and that is the total domination of marker peg runners in any pacing race that matters in the last 18 months.
He won from the Cup from the trail last year and the Auckland Cup, Miracle Mile, NZ Free-For-All, Victoria and Hunter Cups and just about any other important pacing race these days is won by horses saving ground on the inside.
The development of the standardbred has far outstripped that of the already more refined thoroughbred in the last two decades and that, coupled with faster tracks and more aggressive driving, means swoopers are an endangered species.
With key rivals like Copy That and Classie Brigade drawn to get forward and to the marker pegs while Self Assured faces having to move mid-race to get handy, he will be bucking that trend if he is to defend his title.
Self Assured hardly looked the dominant member of this crop when he fell in to win the Flying Stakes two weeks ago after an easy lead, albeit in sizzling late sectionals.
To repeat today Self Assured will need to be better and that is where the fun stuff, the actual horse training as opposed to just feeding and working them comes in.
Self Assured was due for his occasional joint injections (most older horses get them) after Ashburton and they alone have to be timed correctly.
Then Purdon will have called on decades of experience to calculate how hard to squeeze Self Assured, an equation of airway opening and extricating internal fat without inducing lingering fatigue.
Purdon is the best and has been working with today's best horse so if any pacer can defy the marker pegs being the highway to heaven it is Self Assured.
Copy That looms as the huge danger because he feels big and strong when he can lead and roll, almost all his major wins coming from in front.
He may be a more natural sprinter than a true 3200m horse but his brave third in last year's Auckland Cup is proof enough he can win tomorrow.
Classie Brigade clearly can't count because he is basically nine (old) but racing like he is five and his manners and likely field position make him a huge factor tomorrow.
Perhaps the only other winning chance today is South Coast Arden, a steamroller of pacer who will take enormous catching if he bullies his way to the front but he may settle a long, long away from that goal starting on the unruly.
Purdon's other pet project for today Franco Indie should have enough x-factor to outmuscle Republican Party in the Sires' Final.
