Thomas Northcote's maker's marks are quite distinctive and easy to identify.  A range of marks are seen below.

 

Click on any picture to enlarge

 

1780-1784    click on picture to enlarge

1784-1786    click on picture to enlarge   

1786-1790    click on picture to enlarge click on picture to enlarge click on picture to enlarge click on picture to enlarge click on picture to enlarge click on picture to enlarge     

1791/92        click on picture to enlarge click on picture to enlarge click on picture to enlarge click on picture to enlarge

1792/93        click on picture to enlarge click on picture to enlarge click on picture to enlarge click on picture to enlarge

1793/94        click on picture to enlarge

1795/96        click on picture to enlarge