Other mistake: Once Lizzie leaves the castle of Mr. Darcy, skid marks from crew trucks can be identified on the country lane leading away from the castle, where she admired the statues Mr. Darcy had accumulated.
Other mistake: When Darcy proposes to Lizzie notice the clock on the mantle does not change time. Nor does the clock change time when the Bennetts are discussing having the militia leave town.
Answer: The composer is called Dario Marinelli, the pianist is Jean-Yves Thibaudet. Marinelli composed the music that Lizzy and Georgiana play. The only thing he hasn't composed is the piece that Darcy and Lizzy dance to at the Netherfield Ball, which is a piece from Henry Purcell.