I would say they are import marks for Dublin and suggest the sponsor’s mark is S Blanckensee & Sons Ltd. who registered around 1903. The Dublin date letter shows to be around 1930-31.
Is there a duty mark (monarch’s head) next to the Chester date letter?
Unfortunately there is no duty mark - only the Chester assay mark. I agree with you regarding Blanckensee. Looks very much like their mark. That’s what
I thought initially but they were in Birmingham no?
There is a small W to the left of the Chester stamp. Probably the stamp of a journeyman?
This basket has a strange origin:
Made in Birmingham, sent to Chester then exported to Dublin? The Chester date letter is puzzling.
The Chester date letter is “e” for 1930, so probably imported as new into Eire.
Many Birmingham silversmiths sent silver to Chester for assay so, of course, had to register their marks there as well as in Birmingham. The reason seems to be that Chester was able to give a faster turn-round; maybe the fee structure was more advantageous too.