This isn't new. The UK has long had wide-ranging anti-terrorism powers because the IRA were running bombing campaigns in (mostly) London from the late 60s to the late 90s. And every country has different rules for ports/airports, for the same reason they have customs posts there.
The 2000 act listed the IRA as a proscribed group but it wasn't the focus of the legislation.
There were major changes to "terrorism" legislation between 2000-2010. The 2001 and later acts/modifications were more a result of 9/11, 7/7 and the "war on terror" (and the UK being Bush's little bitch).
