
In answer to your questions, YES JRT's are recognized but only with the Irish Kennel Club not the English but Ireland is still part of the UK.
If you import a JRT from abroad it can be shown at Crufts in the Parson Russell Class would you believe!?
A friend of mine qualified hers for Crufts & she lives in France when she phoned our KC in England they said she could show in the Parson Class.LOL
The difference between the Parson & a Jack is size, leg length & temperament, the smaller ones have a much more biddable temperament than the Parson for some reason, JMO.