Just looked in my Albert's Button book .
&
Your Button look's like the NA 112 IMO
&
"Navy; 2-piece with border and circle of rope.
A. The device, eagle facing left, upper fluke of anchor behind left wing.
"R & W. Robinson/Extra Rich" ; 23 mm; pre-1850.
(There are many post-1850 makers and variants , as this pattern was in use until 1941)
Hope this info helps..
p.s. My Book also states that Evans & Hassall. Back Marks date from 1860-68.
This book is Quite a Few years old but I believe est, 98% of the info Within is still accurate.
Davers