Original sentence: He was involved in the campaign's launch in June 2012, delivered a speech on the subject in the annual John P Mackintosh lecture in November 2012, and addressed a fringe meeting at the Scottish Conservative Conference in June 2013
Edited sentence: He was involved in the campaign's launch in June 2012, delivered a controversial speech on the subject in the annual John P Mackintosh lecture in November 2012 (in which he claimed Scots would no longer be able to enjoy British culture if they vote for independence), and addressed a fringe meeting at the Scottish Conservative Conference in June 2013