I think a good chunk of it was probably installed as a consequence of terrorist attacks during The Troubles[1], which led to the "Ring of Steel"[2], a fortified security/surveillance cordon around the financial districts.
If you compare those measures to the US response to Sept 11th and others, I think you'll find a lot in common. I think at the time the measures were widely welcomed by the public too, although I'm not certain.
If you compare those measures to the US response to Sept 11th and others, I think you'll find a lot in common. I think at the time the measures were widely welcomed by the public too, although I'm not certain.
[1] https://en.wikipedia.org/wiki/The_Troubles
[2] https://en.wikipedia.org/wiki/Ring_of_steel_%28London%29