A bit of reality
Who watches the watchers? This man was not involved in investigating any thing in relation to the Police, he was purely working for them in connection with the HR department. Comments 1 and 3 are to be frank a little bit strange but hay ho!
What is a level 5? Well it is publicly available information level 1 is erotic posing, level 2 is solo masturbation or sexual activity between children, level 3 sexual activity between an adult and a child, level 4 penetrative sexual activity, level 5 is bestiality,masochism/sadism in relation to a child.
so "Apparently you can be caught with the most serious type of image, a "Level 5", without anyone having a clue what a Level anything one is" is complete nonsense. You may not know what the levels are but there is NO WAY you could be done without knowing what you had was not legal!
"Don't the police have in-house 'expertise'?" They do as do all large organisations but sometimes a new system or what ever requires some more staff on a temp basis and consultants or similar are employed. If your referring to E-Crime units which this man did not work for then yes they do.
If that sounds a bit defensive, I work for a Police Force doing computer examinations and rather sadly 90% of the work I do involves looking at indecent images and videos of child abuse (NOT porn, as porn can be "exciting") and let me tell you some of these are pretty horrific, and not once have I wanted to download and watch these for fun! Some of the comments do come from a level of understandable ignorance but it is a bit wrong to slate us in the job we do when most people could not do 6 months of this type of work never mind the years I have done.