The other existing blocks are only targeted at the "big players" as they are court orders to specific ISPs, A&A are genernally not included in those orders and

The other existing blocks are only targeted at the "big players" as they are court orders to specific ISPs, A&A are genernally not included in those orders and so they don't have to block them (These orders have been around for about 10 years now). This is a law obliging all providers in the UK to attempt to prevent access to services run by sanctioned people so A&A are caught up in this round of blocking.