From the science of dr Who

http://aboutactorcharlesdance.blogspot.fr/2013/11/charles-will-be-in-science-of-doctor.html

.....Actor Charles Dance did manage to slip a smart ad lib into one segment. Summoned onto the stage to squirt chemicals in colourful clouds through a flame, he remarked: ‘This takes me back.’
Cox wondered whether he was remembering school chemistry lessons. ‘No,’ said Dance, ‘early psychedelic rock concerts.’...

on youtube : http://www.youtube.com/watch?v=yO2YovSZEyA

Charles at 27:40 mn