Yes it most certainly is and there was a VERY famous litter bred by the top breeder Sheila Smith of the famous Salador kennel. She used a Black and Tan dog, Ch: Caderyn Black Tulip to Salador Crumpet(Tri) this resulted in 7 pups of all 4 colours, Sheila was disappointed at first as her longed for Black and Tan bitch was not in the litter, there was a beautiful Blenheim bitch, Salador Cherrybird and a Black and Tan dog who would become Salador Charlock, I quote from her book here "the Blenheim bitch who popped out last of a well marked litter, I got such a shiver down my spine!". But it was Charlock who was to go on to be something REALLY, REALLY special for her, he would win over 40 1st's at Champ Show level (never got a sniff at a Challenge Certificate however!) but it was as a stud dog that he would be most famous, going on to sire the Crufts Challenge Certificate winning Ruby bitch Salador Coppergleam, also Ch:Rheinvelt Ringold Von Salador who was also a Crufts Challenge Certificate winner too. Charlock despite his broken colour pedigree reverted to being wholecolour dominant and was considered, even to this day actually, as one of the most influential wholecolour stud dogs ever, if you have a UK bred Black and Tan then you will almost certainly find him in that dog's pedigree somewhere in the past! Sheila goes to tell us that in his twelfth year he was galloping across his paddock at home when he collapsed and died shortly afterwards, "He never ran up a vets bill in his life and he didn't at the end" she tells us!!
I was also on a well known wholecolour breeders website the other day when I spotted a Blenheim, unusual for them, on looking at the pedigree she has a B/T Father and a Ruby mother!! icon_nwunsure How did this happen I hear you ask? Looking further back into her pedigree she has Blenheim behind both parents and this time it threw forwards!!
Ah! The mysteries of colour inheritance eh??