[dingaling]

The Internet Watch Foundation can't tell anyone to do anything. It's just a private company based in Cambridge:

Company No. 03426366 Status: Active Date of Incorporation: 29/08/1997

Some organisations ( fewer than 100 ) have entered into voluntary commercial contracts with the IWF that oblige them to self-implement the list provided by the IWF.

[makomk]

They're "voluntary" in the sense that the Government told them to voluntarily filter internet access according to the IWF list, or the Government would pass a law forcing them to do so and it'd be a lot worse for them than just playing along.

[lmm]

Voluntary? I thought it was required. Are there ISPs that don't?