Is the picture from this season? I'm sure I've seen this bag but it wasn't recent and unfortunately I can't remember where I saw it (Prada maybe?). If MN can't give you the answer I'd try The Purse Forum, they must know.
I think I've found it but it appears to no longer be for sale, shame as it was somewhat affordable. It's a laptop bag by Knomo London, the Rubi in smooth leather, the 17" model had the longer handle by the looks of it. Campaign pic attached.