That is indeed "black'n'tan". It's got a white line below the black roof.
What may be confusing is the full-height orange/tan band round the lower sides. It was more usual for the smaller, lower, dipped orange/tan along the side. Other versions during the 1960s had locos in all-black, no orange at all, with white line, or same with a yellow patch on the front.
"Supertrain" was all over orange, roof included, with broad black band round middle. That was introduced in 1972 and with nothing more than a new logo and new white lines, changed into the "tippex" livery in 1987.