Plus Irish isn't a race, you can't be racist towards a group of people that aren't classed as a race
You can.
It's amazing how many British people don't know race laws.
Since the Race Relations Act in the 1960's any hatred or discrimination on the grounds of race, ethnic origin, ethnic identity, nationality, religion etc is classed as racist. It's a way of grouping together similar crimes and it's been this way for over 40 years.