Custom, not a Convention

This is Swan Upping week, and so a procession of boatmen (and boatwomen, one assumes) are making their way along the Thames to count and mark its swan population.

Almost as worrying as the widespread student belief that this is a constitutional convention (it has no constitutional purpose, being a larder check / conservation exercise, even if a rather quaint one), is the large Daily Mail coverage of the event. What can this mean ?