Hello, I have thoughts I would like to add to what Impulse and AG2012 have said.
Although Impulse’s pictures have gone now, my thinking about the “crab” mark on Impulse’s and other similarly marked spoons, is that a “crab shape” was the obvious shape to mimic the “lion passant“ mark that is on English hallmarked silver. A crab like mark is commonly present on diverse makers’, early electroplated, spoons as a “pseudo hallmark” possibly for financial gain. I do not think the presence of a “crab” mark in isolation is a reliable feature to identify any particular company. Regarding the crown marks, you need to remember a “crown” was the official mark of the Sheffield Silver Guild and its presence on electroplated items could also be used to advantage. We know there was legislation in 1896 to stop the crown mark being put on silverplated items. Lots of Elkington’s early stuff (before 1900) had a crown in a shield mark, although that company did have Royal warrants so perhaps they were allowed?
Moving on to the “AS” mark possible “Aluminium Silver”, Impulse could be correct. F. Whitehouse has “AS” as “Afghan Silver”, William Naylor has “Australian Silver”, Joseph Gilbert had Argentina Silver and currently on the web site "silvercollection.it", a generally excellent reference site, “Aluminuim Silver” is said to be a trademark of “Daniel&Arter”. I have not seen that “Aluminuim Silver” mark before. However until very recently, I had also not seen the mark shown in the below image.
Here we have a “D&A” mark with ”Diamond” spelt on a spoons stem. Is “Diamond” another “Daniel&Arter” trademark, but as yet unrecorded? These spoons were more decorative than the usual utilitarian cutlery we see from the D&A. The “C” in a diamond (unsurprisingly?) does not seem to have an obvious meaning. I do not think is for the standard of electroplating, could possibly be for “company” but could just be a pattern indicator.