Counting only Cornish?

Cornwall Council Tweets to say:

"Our campaign to get people who call themselves Cornish to say so on the Census has made it onto wikipedia http://bit.ly/h9qKX3"

I have asked the obvious question, namely if we can now look forward to a "council campaign" for people who consider themselves English, Scottish, Welsh, Irish, Jedi etc etc to say so on the Census. I can understand why the council would want to campaign for maximising overall participation, but I'm puzzled why this campaign should be limited to those who call themselves Cornish. Does nobody else pay council tax?