..yep, there was an article by Marcus Armytage at the weekend saying Irish horses might not be able to compete in the Grand National. Not sure what it means for Cheltenham, but Australian and US horses run at Royal Ascot without any bother.
However there is legislation covering that , potentially there won’t be with a no deal
As it happens I think a lot will or rather could probably be resolved in time to not make a huge impact but an impact there certainly will be . If your involved in a sphere which could be effected though it seems perfectly reasonable to be concerned.