So you all believe that the antivax kids, who are disease free, are spreading measles. Nothing to do with the third world were importing?
If we vaccinated all people in this country then isolated ourselves completely from the rest of the world then yes, we would be entirely free of measles and no one would need vaccinating against it. Bit of a high price to pay though, isn't it? No foreign holidays, no foreign imports, no foreign trade at all. It's not very feasible in today's world.
So, we are going to have contact with foreign people who may be unvaccinated and, yes, may carry measles. Say they come into contact with an unvaccinated British family while said family is on holiday. The four children in said family then come back to the UK and expose everyone in their schools, nurseries, sports clubs etc to it. In their secondary and primary schools they encounter fifteen people in total who cannot be vaccinated for one reason or another. Who then contract measles. The smallest child goes to a day nursery, where she exposes her fellow three year olds to it. Eight of them have siblings under the age of vaccination, who they then pass it on to. Some of whom die, some of whom sustain life changing injuries as a result.
Yes, the unvaccinated-by-choice kids are posing a risk to the unvaccinated-by-necessity kids.