Under categories (lhs) you should see Ely Eventing Centre, click on that and then you'll get the options of the day, then XC or SJ, then Photographer 1 or 2.
Like this for 20 October. 21 and 22 have different options because there were the two classes on each day.
Bear in mind that when I looked for the 22nd, the pics from XC had Intro and PN mixed up for photographer no.1
So some of the PN pics were under the Intro heading and vice versa