Here is a proof that Aby Ruddy is dominant to Tawny Tabby.
This pedigree shows starter Neila hides Tawny Tabby:
Now look at this pedigree:
Remember Neila hides Tawny Tabby.
Therefore Neila's son, Tawny Tabby Hider, hides Tawny Tabby, since he shows Siamese Lilac.
But Tawny Tabby Hider's daughter in the above pedigree is showing Aby Ruddy.
Since Tawny Tabby Hider has Siamese Lilac showing and Tawny Tabby hiding, the daughter's shown fur must have come from her mother, Aby Ruddy Hider.
Therefore, the daughter's hidden fur must have come from Tawny Tabby Hider, and must be Tawny Tabby, since Siamese Lilac is known to be dominant to Aby Ruddy.
Since Tawny Tabby is hiding behind Aby Ruddy in this cat, Tawny Tabby must be recessive to Aby Ruddy.