Purcell's Dido and Aeneas is currently at the hub of musicological debate: when was it written and for what sort of performance? One indisputable fact is that it was originally prefaced by a Prologue, the music for which has been lost - with the possible exception of an overture marked in the source 'Overture to Mr P's Opera'. This, together with a number of dance pieces from about the same period (the late 1680s) and a duet from Dioclesian, was included on Monday in Curtis Price's reconstruction. Such an attempt to present Dido in something approaching its original theatrical context is typical of the English Bach Festival's pioneering approach to the performance of early opera. Visually it was very appealing: the costumes were made of gorgeous stuffs of gold and bronze which glimmered and shimmered in the warmly-lit closing tableau, and Sarah Cremer's choreography was convincing and well executed. What a shame, then, that musically it was as flat as a pancake. The only saving grace (and it was a major one) was Della Jones's Dido. She sings a poignant Lament, but she was also made to double, less successfully, as the Sorceress. This can prove acceptable in the concert hall, but was dramatically disastrous here.