This is indeed a Stafford the colour is open for interpretation, the body and the nose are certainly liver.

The leg and face markings are those one would expect to finds on a black and tan.

Liver may also be lighter in colour but the give away is the NOSE leather colour. In a liver it it brown or dudley.

This is a black and Tan but only carries one part of the gene the legs and "thumb prints" are brindle.

This dog is quite clearly black and tan with white and carries both side of the gene.

The breed standard states, Colour:Red, fawn, white,black or blue or any of these colours with white.Any shade of brindle or brindle with white.

Black and tan or liver colour highly undesirerable.

This in  itself is, as always open for interpretation.