In the early days of Northern, they had several attempts at getting the livery right. They included angular “Starsky and Hutch” style stripes and this one is white on violet. They did do an inverse violet on white but neither lasted long as the white quickly became stained with rust from the cast iron brake blocks. Eventually they settled on lilac and blue.
<a href="//commons.wikimedia.org/wiki/User:Rcsprinter123" title="User:Rcsprinter123">Rcsprinter123</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>