I have embedded your picture here for the benefit of those who prefer not to click on links.
As your picture only shows the Elkington mark and not the sauce boat itself your question cannot be answered. I can, however, tell you that the mark includes Elkington's date letter "M" for 1898.
We normally reckon that numbers of the form you have found on the bottom of your sauce boat are pattern numbers. These would be used within the factory but have no other significance.
The footed form of the sauce boat is not uncommon although I note that it is fairly small - perhaps intended for one person or for a small amount of sauce.