The seat numbers suggest that you were flying first class. The air personnel is much more forgiving when you are in that category. I flew few times with a Brompton as a carry-on and found it far too much stress than it is worth. Even though I was successful I expect statistically to end up with charges for a bike or excess luggage and haggles with air personnel. Putting the bike into check-in luggage involves no stress if you meet all limits.