Or is it a double sculpture? Was Mrs Lincoln famously invisible?

I passed an interesting statue in Parliament Square this week. 

As you see, it's a statue of Abraham Lincoln, and a chair that he's not sitting in. I wonder what happened here. Perhaps the sculptor was famous for his lightning speed, and by bad luck happened to begin work on what was intended to be a seated sculpture at the very moment Abe got up to answer the door. Or perhaps the chair is also famous. Perhaps in the world of chairs and chair-fanciers, this is known as the Parliament Square statue of an eagle-back scroll-legged cabriole chair (partially obscured by bearded man). Or perhaps it's intended as a symbol of what a virile, dynamic president Lincoln was - 'This here's a chair, but you won't find Honest Abe lounging about in one o' they! No Sir! He'll be up and about, pulling at his lapel, and slightly flexing one knee! That's just the kind of man he was.' Perhaps this inspired a whole movement in presidential sculpture of which I'm unaware- Eisenhower with a bed he's not asleep in. McKinley in front of a big pile of cakes, not one of which he's scoffed. Hoover and a pretty frock he's totally not wearing. Clinton turning his back on a disappointed Monica Lewinsky. I hope so.