along with shastar vidya and the dasam granth, raag vidya (science of music) was banned by the british, as this was what gave sikhs the warrior power, and if removed, the sikhs would forget their identity and source of power. Also this is why there is no dasam granth inside Golden Temple, as they were removed, yet inside Non-Panjab Gurdwara Takhts (Patna Sahib -Bihar and Hazoor Sahib-Nanded) There is dasam granth, as the british never bothered with sikhs there.
now if you look at kirtan done at the gurdwara, have u seen raagis playing the following instruments, Saranda? Taus? Dilruba? NO, thats because the british banned them, and force fed us that incredibly boring instrument, vajaa (harmonium), which is a french instrument, not hindustani. Saranda was an instrument invented by guru arjan dev ji, dilruba/taus was invented by guru gobind singh, and now what do we have to show for their inventions, nothing! Raag Vidya was practiced especialy by Khalsa sikhs and sufis, now that Sufis have gon to pakistan, we have lost the knowledge and authenticity of the technique. Just like how we have lost genuine raag vidya, we have lost SHASTAR VIDYA, and now theres controversy over dasam granth. Had the british never meddled, then there wud b no conspiracies and doubts about whats original, genuine etc.
Luckily there are some groups/ppl who are trying to bring back raag vidya traditional instruments - watch the first two videos especially, lovly jubbly!
especially watch the Rabab/Saranda video, at 4:02 listen to wat Professor Surinder Singh Says