Jerry Cornelius wrote:But Ditch, you've cut the wrong end off!
Jerry; Closely examine the bottom edge of the photo ..... See the 'extra' beneath the round?

That's the side of the tin. And the big shadow, on the left side? That's cast by the tin.
I'd never actually stopped to give any of this any thought before. But, Kay - Jay appears to have got it in one; They have a 'deep' end, so they can store the yeast and such in there. Makes the lip too high for a tin opener.