The assassination attempt on Robert Peel was in 1843, three years before the Corn Laws were repealed in 1846, not on the day after as depicted.
The Corn Law debate was in 1846, so it is reasonable to assume that is the year this is set in. Therefore Ernest would not have been playing Wagner's Bridal Chorus (Here comes the bride) from Lohengrin that year, since the opera premiered in 1850.