It did point out that I was wrong about no mass shootings (p57):
"In 2010/11, the police provisionally recorded 642 offences of homicide, which includes the 12 people killed by Derrick Bird in June 2010. Homicide offences increased by four per cent (24 offences) compared with 2009/10 (Table 2.04).3 Caution should be taken in looking at short term changes in the number of homicides, as they can fluctuate from year-to-year. For example, the rise in homicides this year follows a fall the previous year"
But the dead giveaway is buried in a footnote on p58:
"As measured by the Homicide Index. The number of currently recorded homicides peaked in 2001/02 at 794. There are more currently recorded homicides for 2002/03 (943), but these include the 172 victims of Harold Shipman, which were all recorded in 2002/03 but took place over a number of years."
Harold Shipman was a doctor who spent a large part of his career murdering elderly patients with medication. The huge spike in John Lott's graph is almost entirely due to this one set of crimes being recorded in 2002/03.