A blog post recounts a mass telepathy experiment organised by the SPR in 1927:
http://www.weirdhistorian.com/the-great-mass-telepathy-experiment-of-1927/
The experiment was alo recently covered by Massimo Biondi:
https://psireport.wordpress.com/2017/12/27/radio-esperimenti-di-massa/comment-page-1/#comment-198
The experiment was reported in the SPR's Proceedings; it can be found in vol, 38, in an article by V J Woolley: 'The Broadcasting Experiment in Mass-Telepathy'. The article can be read in the SPR's online lbrary.