The OP was probably referring to Northern Ireland, which is a devolved part of the UK (and uses GBP) - Whereas your article refers to the Republic of Ireland, which is in the Eurozone.
If OP was referring to Northern Ireland, then s/he should have said so, since "Ireland" generally refers to Ireland, and Ireland did secede, while NI did not.
Isn't this more complicated than that? Declaring you've 'Seceeded' doesn't mean a new state is created/recongnized; there's a county in Iowa that 'seceeded' but it didn't change anything. Just sayin, how many people on the street know about anything but their hometown much less than the internal politics of Ireland.
Nothern Ireland is a part of the UK. So it definitely did not seceed from the UK.
The Republic of Ireland, is a seperate country with completely different government and currency, that used to be part of the UK but isn't any more, so it has definitely seceeded.
That county in Iowa, it is actually still part of the USA and has not managed to separate itself either legally, economically, or through force of arms. It is clearly not a separate sovereign nation. It has not seceeded from the USA.
No. Northern Ireland didn't secede in any sense. It's the rump of the Kingdom of Ireland within the United Kingdom. The 26 Counties seceded from the UK to become the Free State, while NI stayed within. This is regarded as partition, not secession, and happened before the secession of the South. The partition was performed by an Act of the UK Parliament, and secession was performed by the Anglo-Irish Treaty.
All this is pretty well documented as it was of significant historical importance, much more so than the reorganisation of the borders within a US state.