[rmc]

How is it that Spain/UK with active terrorist movement did not have those laws before ?

They (the UK) did. They had the Prevention of Terrorism Acts in the 1980s. They had interment without trial. They had aggressive police on the streets. They had police shooting at protesters. They had the head of government (Thatcher) saying "We don't negotiate with terrorists". They had secret service spying on people of the wrong ethnicity.

I remember going to Northern Ireland in the 90s and being questioned by military with machine guns at the border. These things did exist.

[peterstjohn]

Let's also remember that for a long time, several political parties were also not allowed to have their voices broadcast, either.

[gsnedders]

On the other hand, a lot of these things only applied in NI, not in the rest of the UK.

[rmc]

The IRA almost killed the UK Prime Minister. It was hardly a trivial matter.

[pbhjpbhj]

... and bombed Manchester (1996); Birmingham; Docklands, London (1996); Omagh (1998) at least.

[gsnedders]

Omagh is NI; but the important point here was the militarized police force was (for better or for worse, given the number of mainland attacks) confined to NI. Much of the special powers granted only applied to NI. I'm not saying it wasn't a problem on the mainland — by any measure, it was — but one must realize the extra powers granted were limited.