Yep.....Chester Sterling....and the A is the date....the absence of the monarch head....indicates between 1889 and 1923.....with 1926 being the only year in that time frame with an a of that type.
Can't find the maker though.
Linda C

ILS & Co?

The three worn rounded things in a shield is probably the city of Chester's assay mark (sword and 3 sheaves of wheat), and the ?LS&Co would be the maker's mark, which may be hard to track down.

Now it's a matter of checking every reference you can find for a maker using that mark who was in business in or near Chester in 1926 ... and Liverpool is a nearby large town.

City directories showing jewelers and silversmiths would be where I would start.

That's a really good picture. :)