In a slight departure from The general NH profile, we are urged to consider first the jockeys at Carlisle. In particular we have to look at the leading jockeys for the course, on winning volume. Of those, seek the best on form. It's only a slight variation on the normal approach but the subtle change makes all the difference.
Short list horses in the weight brackets of top-weight and middle-weight (defined as 10-10 to 11-3 with exceptions if lowest weight much above 10-0). In the list seek lightly handicapped horses (no more than 3 handicaps raced) and/or distance winners. Look next at the best previous form among those selected. Look next among those left for trainer with the best record (in-form or course or winner of this race last year).
Cat Six WAS the selection based on this profile. However as is all-too-often the case I employed my own better judgement on noticing he was carrying 7lb extra and remembering that on some occasions in Handicap Hurdles like this, such an impedement is enough to stop a horse from winning. The key here really is that no other horse had comparable form which is why I settled on Douryna despite not even a place. Next time I hope I'll know better.