The BBC just can't help themselves

So what do you see happening in that piece of video? I see Boris Johnson wading through knee high water when the riverbed gives way and he sinks up to his waist before being helped to his feet by the lady accompanying him and a couple of others.

The BBC describe the event thus

"The Mayor of London Boris Johnson has fallen into a river while launching a drive to urge Londoners to volunteer.

While helping to clear up the River Pool in Lewisham, south-east London, he tripped and fell in, getting wet up to around his chest, then stumbled away.

Mr Johnson was helped to his feet by volunteers who he was helping remove litter and plants from the river. He thanked them as they helped him up. "

And the headline they choose - "Boris Johnson stumbles into river"

Now are the BBC lazy, incompetent, biased or all three? Their copy says that he "tripped and fell in" then "stumbled away" but the headline says "stumbles into river", why the disparity? Could there be some political bias in the choice of words? What do you think?