But only 1 of your flights was UK domestic -- the point at issue -- the others were inter-European (which don't have any special customs procedures). It is only when taking a UK domestic flight that the special tagging and segregation of baggage occurs (as all the other domestic baggage isn't going through customs), and how well that works probably varies by individual flight. I've done it twice and once was quite fast, the other time it took hours. Both occasions coming from BA F, but of course UK is Y only service (in any case the delay is from customs and not the baggage handlers).