Okay I'll play along.
Arrive at the bus stop just as an MK bus pulls away.
Wait for next bus = 20-30 (most likely not 30 minutes, but it could happen)
Ride to MK = 20
Walk from bus to ADR = 10
Now granted that's only 50-60 minutes. But they do like you to check-in for your ADR 15 minutes early. So that estimate of 80 minutes is high, but it's not that far out of the ordinary is all I'm saying.