In the UK, 'Plaid', capitalised and in writing, usually refers to https://en.wikipedia.org/wiki/Plaid_Cymru . It's not pronounced the same as 'plaid' though.
Joking aside, I also read the title as referring to Plaid Cymru and was very confused.
https://en.m.wikipedia.org/wiki/T._P._O%27Connor
In that case, the objective was to argue for home rule for Ireland. And to look out for the large Irish community in Liverpool.
http://www.tartansauthority.com/highland-dress/modern/flypla...
"Plad" [ie tartan-y cloth] is USA pronounciation to me; which I assume is what you mean in your second sentence?
"Played" of course also means "to be conned".
"Plaid" in "Plaid Cymru" is pronounced like "plied" in English.
Is Plaid Cymru pronounced 'Pllad' ;)