I love this kind of british humour, however crude. In my mind, it's similar to the campaigns (most years?) to have a non-christmas song be the #1 christmas single.
Boaty McBoatface must be the least crude name someone could come up with ;)
There's nothing particular English about "Boaty McBoatface" to my mind, it's just standard internet humor.
It's absurd and mocks authority, which are staples in British (not just English) humour.
Exactly, if they (Gallup?) had decided that Rage Against the Machine's Killing IN the Name Of could not be UK Christmas Nr1 it would have been even sillier. As it was it was just the right amount of protest and respect from both sides.