Homer,
 
Several small tidbits for you to move forward on . . .
 
first, J. P. Cushion's volume "Handbook of Pottery and Porcelain Marks" lists
a patent applied for by Maddock and Gater on June 12, 1875 (Parcel no. 6,
Patent No. 292035).  Maddock and Gater were apparently based out of Burslem,
which in this case makes sense.
 
you also want to check Godden under Gater.  there is some good information
regarding his firm, which appears to post-date the mark cited in Cushion.  it
seems possible (likely?) that Gater possibly worked for Maddock before
undertaking his own works or some sort of cooperative venture was undertaken
by the two in the 1870's.
 
anyway, hope this is somewhat helpful.
 
cheers,
 
m a sterner