Police are looking for barrister Paul Powlesland who held up a blank sign and only said we was going to write "not my king" on it:

https://twitter.com/paulpowlesland/status/156935177260655002...

Or, more precisely, he was going around with this blank sign, asking officers whether he would be arrested if he were to write that on the blank paper, according to the account here:

https://ca.sports.yahoo.com/news/man-said-warned-risked-arre...