The first thought that popped into my head was 'scare-mongering'. The company behind this even has the motto 'turn piracy into profit'.
From the article
Michael Coyle wrote: said: "The cynical lawyer in me would say this is a money-making exercise.
"If you send out 10,000 letters and ask for £500 each time, you only have to get half to pay up and you've made a significant amount of money.
"Because it is porn, the person who's being accused won't want to go to court and is more likely to pay up to make the matter go away even if they are completely innocent."
I don't fileshare, but I do use TOR software to hide my tracks and my I.P. I'm curious to know how effective that is now...
Plenty of people in the UK still have unsecured networks, and even encrypted networks are vulnerable, thanks to some very clever software developers.
I'd be interested to see comment from tech-savvy members on this issue.