After this a number of other collections of pibroch and light music were published. This pibroch appears in the Campbell Canntaireachd MS. The role of the pibroch may inform the performers interpretative expression of rhythm and tempo. Watt's own bagpipe compositions are influenced by Simon Fraser's pibroch style. The written notation of pibroch serves mainly as a rough guide for the piper. A number of pibroch collected by MacKay have very different titles in earlier manuscript sources. The modern revival of pibroch was initiated by the newly founded Highland Society of London. This pibroch is entitled "Glass Mhoier" in the Campbell Canntaireachd. Most pibroch are commonly assumed to have been written during the 16th to 18th centuries. Breton piper Patrick Molard organised the first pibroch recitals in Brest and Paris in 1992. The Pibroch deteriorated further as time passed, and her bulkheads began to give way. In musical structure, pibroch is a theme with variations.