These chips were originally issued by Grosvenor Casinos in England in 1997.
Later made with Eurocoin backs like the ones in the scan. These have Grosvenor Casinos on the rim. That may be the reason they were notched. I can't think of any other reason an advertising chip would be notched.
I have one with Clint Eastwood in color.
I have 4 each with Clint in B&W and Gene Hackman.
$7 each including postage.