For 25 years my mother lived on the Isle of Man in her retirment. It was my contention that, because they were a known pathway from Ireland (both sides) they were particularly vigilent. Leaving LHR or LTN, my boots never sounded the old style metalic hoop. Leaving IOM - went off every time. They swore blind that their system was set to the same tolerance as the mainland.
I've not been since 2017 when my brother and I took mother's ashes back to place in the top of the grave of her second husband.