Don't get too carried away Campion, he had been a forensic scientist since the mid sixties, specialising in firearms and gunshot wounds.
It would be a very tall order to dismiss his position as an expert, the same would go for Dr. Vanezis.
Firearms crime A Home Office study published in 2007 reported that gun crime in England and Wales remained a relatively rare event. Firearms (including air guns) were used in 21,521 recorded crimes.
It said that injury caused during a firearm offence was rare, with fewer than 3% of offences resulting in a serious or fatal injury.The number of homicides per year committed with firearms remained between 49 and 97 in the eight years to 2006.
There were two fatal shootings of police officers in England and Wales in this period, and 107 non-fatal shootings - an average of 9.7 per year over the same period.
In 2005/6 the police in England and Wales reported 50 gun homicides, a rate of 0.1 illegal gun deaths per 100,000 of population. 6.6% of homicides involved the use of a firearm.
For international comparison, in 2004 the police in the
United States reported 9,326 gun homicides.
Wikipedia
I would much prefer to use the Home Office figures, but I'm working this evening, so have little time to search for these.