There is no way of telling if June 2015 was harder than June 2016 until Edexcel collect everyones marks and compare them to the statistics of last year. In terms of June 2015 being considered the worse exam ever, it wasn't. I believe that title goes to Nov 2012. But again that's just opinion. Believe it or not, with the grade boundaries quite low for A* at 155, only 5% of people managed to get this mark or higher. Therefore, if you perform in the top 5% of the cohort you are likely to get an A*. A* could potentially be 190/200 if 5/10% of students get this. You never know until the results are published. Personally, from sitting the exam in June 2015, November 2015 and June 2016 I can say that I personally found the noncalc of Nov 2015 the hardest due to the vast amount of proof questions (about 10 marks overall). And many people were bothered about the June 2015 sweets question, but that had come up before in other areas of mathematics.