TYB
Support for Palestine and the plight of the Palestinian people having had their country invaded and occupied, is strong amongst some Irish who see their country (Ireland) as being occupied by the British.
Not all. Irish 'loyalists' are loyal to the Crown and want to be British.
This is the main issue of the historic troubles in Ireland.
The Celtic team is against British occupation as they see it. And so they sympathise with the Palestinians and fly Palestinian flags in Belfast and other areas.
Winner