Despite the denials, the answer is most likely this was all coordinated with LEAs.

  Some artists have questioned if Banksy, once considered anti-establishment, now enjoys special treatment from Britain's powers that be.

  In 2014, Vice Media asked: 'Why Is Banksy the Only Person Allowed to Vandalize Britain’s Walls?' The story quoted David Speed, a street artist who ran a British graffiti collective. "It's very much one rule for him and another rule for everyone else ... When street artists do it, it's vandalism. When Banksy does it, it's an art piece."

  Contacted by Reuters, Speed praised Banksy as "a really important artist of modern times." Yet he still wonders why "one artist should be able to have carte blanche and everyone else would be subject to penalties."

Not sure I agree it’s “most likely” when the linked article presents no evidence of LEA awareness or complicity, just one person speculating.

I know firsthand what can be done with a hardhat, clipboard, and high-viz vest. IMO it is far more likely that Banksy is just really good at social engineering in ways that other street artists are not.