Past grade boundaries for A and A*:
Jan 2009: 60
Jun 2009: 67
Jan 2010: 59
Jun 2010: 62 (68 A*)
Jan 2011: 61 (68 A*)
Jun 2011: 65 (70 A*)
Jan 2012: 65 (70 A*)
Jun 2012: 64 (69 A*)
Jan 2013: 62 (68 A*)
Jun 2013: 50 (57 A*) (01), 61 (67 A*) (01R)
Jun 2014: 60 (66 A*) (01), 60 (67 A*) (01R)
Jun 2015: 59 (65 A*)
Average: 61.1 (66.8 A*)
Today's paper was definitely not as difficult as June 2013. The polls show that people thought last year's paper was slightly more difficult.
I'd guess similar boundaries to June 2014; A – 60, A* – 67.