Each route, e.g. BHX-ORK, gets a number of actual routings, and a specific flight on a specific day will be assigned one of those. That would explain why the route varied.
I'm surprised DUB-BHX normally takes you 55 minutes: the block time* is only 1 hour. Moreover, DUB-EDI is as the crow flies longer than DUB-BHX, at around 182nm verses 174nm, and I've done that route in less than 35 minutes. Additionally, DUB-BRS is a few nm longer than BHX, and I've also done that route in under 35 minutes.
* Which includes the flight time, taxi time at both airports, and time for short delays.