Cillian Murphy and Danny Boyle fear they could never make ’28 Days Later’ now.

The star and director of the 2002 zombie flick say the opening scenes in a deserted London would be impossible to obtain and only happened due to looser security pre-9/11.

Cillian, 46, told NME: “The world changed after (we finished shooting) because of the September 11 terrorist attack.

“We’d have never got access to Westminster Bridge, put half a fucking bus down there by Number 10 (Downing Street) now. We had total access. That would never happen now. That time is gone.”

Danny, 66, also told the outlet: “The central city security was almost unrecognisably relaxed compared to what you will understand as city centre security now. That changed with the millennia and we benefitted from deciding to shoot those early mornings in July.

“We hired all these girls to be traffic marshals. One of them was my daughter who was 19 at the time and they’d say, ‘Would you just mind waiting here? We’re making a film…’ It’s just bizarre the way it worked.”

Cillian also said about changing his character’s accent: “Jim was written as English – and I was doing a terrible London accent (in the audition.)

“It wasn’t really connecting but Danny kept asking me back, which was really nice.

“I was in awe of Danny, having grown up on (his films ‘Shallow Grave’ and ‘Trainspotting’), you know, before I was ever an actor. Then they said ‘just play him Irish’ and when I played him Irish, I kind of unlocked something.”