Stewart Dawson & Co Ltd Teapot

Hi we purchased a teapot from Trademe NZ - the item was listed as a Wilcox 1882 US Teapot. On receiving the item we found it is marked. SD&Co Ltd EPBM it also has the numbers 8879 and 5 Gill on the base.

From this site it would appear its date is 1910-1924?? but we are guessing.

Could anyone advise the possible date and value of this item?? and have we dipped in in regards its value versus a supposed Wilcox.

As you may gather we know very little about silver as this was purcahsed as a present for my sister in the USA who does collect stuff.

Any Information will be gratefully received. Actully going though all the silver stuff and this website to find out what it is has been interesting.