Share 'Black in coat on red setters'

In my current litter, I have one boy with two black spots in his coat, just above the croup and going down his left side (see pictures). Having asked around I have heard of at least six other combinations where this has occured and I have also had a particular dog's name mentioned in connection with this. This dog lived in the UK 35-40 years ago ... and yes, I have checked and the combinations...