to Ireland, Northern Ireland or Ireland?

I think not because people go to shows in N.Ireland at any rate, all the time.  Do they have a Pet Passport?

Northern Ireland is part of the UK, therefore no passport required.

Legally you need a full pet passport to go from mainland UK to Southern Ireland.

Worth asking those who come back from the Irish circuit at the weekend if they had any issues re going from mainland UK to Eire. There were talks that they would be checking between NI and Eire but not sure how that would be monitored?

Whether they check it or not, personally I don't think it is worth the risk of NOT having a pets passport where it is legally required. Even if only one in a thousand were checked, I wouldn't want to be that one having to put my dog into quarantine.

Exactly, I'm sure few checks are made in mainland Europe where border checks are virtually non existent, doesn't change the fact that to be legal they do require passports. 

I'm sure the humans could get away without passports but if stopped would be in a one hell of a lot of trouble (except most of the countries also have ID cards which are accepted for travel between many European countries).

i agree with goldmail went to S Ireland August took 3 dogs had passports for all and injections up to date and k/c done wasnt asked going out or coming back for anything BUT aso previously said wouldnt risk NOT having any paper work etc up to date you just never know!!!!

Bit of a step away from the OP but if Scotland do decide to separate from the union will those attending shows there in future need pet passports, and will they still be under the control of the KC, one assumes not.

If Scotland voted for independence yes would need a passport to travel to Scotland. As for shows and KC I suspect the Scottish Kennel Club would remain affiliated with The KC in order to run shows as they do now BUT they could opt to go the route of Southern Ireland and affiliate  with FCI but I think that is very unlikely.