There images I hasten to add are NOT pornographic but not the kind of pictures (body piercing of genitlia(not erect)) etc that a civil servant should have on a work PC.
I don't know when I had the task of being the porn police at a local authority which had just implemented a PIA proxy blocker which blocked the user until they explained themselves. It was a 30min admin role to unblock the retired doctors in sexual health. It was only solved when I blocked the local football clubs website before some special tickets came on sale as per official policy on none council business with high traffic loads. Which then got me access to the head of council (well he came steaming round the door swearing) and he authorised them to be exempt from the proxy server. As he put it "John was my wifes gynaecologist for 25 years the man deserves a Victoria cross" HR were not happy from a policy point of view.
I wish you all the best, the more I hear about office politics in the Civil service the more I think the whole thing stinks.