Is anyone else puzzled/amused?

Throughout the current series of the Transatlantic Sessions, which I think dates from 2010, there has been a mandola/bouzuki/cittern thingy (can't tell which from the telly) parked, complete with capo on the third fret, in front of the piano. Looks to me like a Sobel. I've never seen anybody play it and it usually goes missing for one number in each programme only to mysteriously return!

Is this some form of product placement or something entirely more sinister????

I can't be the only one who's spotted it.