I am very excited that my book project on the history of the NUS policy of no platform in the UK is moving forward. At the moment, I am on the lookout for further primary sources from no platform campaigns from the 1970s to the present (particularly from the 1980s and 1990s). So if anyone has any material relating to specific campaigns, please send an email to email@example.com.
I am especially interested in any material relating to campaigns to prevent Enoch Powell and representatives of the apartheid regime in South Africa from speaking on university campuses in the mid-to-late 1980s.
In the meantime, you can also read this book chapter which gives an overview of the no platform policy in the 1970s and 1980s.