I got a simular colored roo one time from a cross of a Barred Rock roo on a RIR hen. I have been talking to Krys109uk for a while about buff barred birds, so I think I may be right in telling you if you breed him to that RIR hen, you will start getting some red-barred colored birds.
So breeding a that rooster to solid reds hens will possibly yield red barred offspring. Breeding a RIR rooster to BR hens will yield black sex link, right?