How did this fit under the barrier?

You have inside information dear LGM :~)))

Hi Nick,

The answer is quite simple, it started behind you, sailed round the world, (since we know the Earth is a sphere), and now it has almost completed its journey!

Or, theory 2, the ditch that we have to dig round every car park to stop the 'pike..men' putting their caravans there got flooded.... And it sailed!

Best Wishes
Peter

In a roundabout way you may be right Peter :) All the best Nick

Since you are obviously oblivious to what goes on in these ships it's no wonder you are left in the dark as to how it might have got under the barrier. Do you not know these big ships have huge bouncy castles for the kids and so it was bounced over the barrier, along the shore then back into the sea by too many bouncing at the same time.
Or theory No. 2: sail-away party got out of hand!
ps I love to cruise but this looks a little too big for me too. Great shot. ~Herb