[aliher1911]

In all fairness the highway code specifically says that you should not violate it to let ambulance pass. Might be down to sketchy council, but they normally place signs "new layout ahead" and the like when limits, lanes change.

[mjmas]

Violating other road rules to let an emergency vehicle through is particularly allowed under the road rules where I am (Queensland Australia)

[int_19h]

In US, it's not uncommon for small towns to have traffic fines be a significant part of their budget, which in turn incentivizes them to deliberately confuse motorists to fine them - this is especially true for towns located on busy routes where there's a lot of out-of-town traffic, since locals generally learn the where the traps are.