why do you assume it's just the uk that criminals move to? (It's not).
(From the Irish Police Conference)
"The Association of Garda Sergeants and Inspectors earlier called for the establishment of a Europe-wide criminal database so garda� will know if convicted criminals from other countries are coming into Ireland.
The AGSI conference in Co Meath has heard that a number of immigrants with convictions for serious crimes, including murder, have entered Ireland.
These people should be required to register at their local garda station within 48 hours."
And it seems this would be an issue in every EU state.