Maltese Cross Mizpah Brooch Authentication Issue

Dear All
I have recently purchased a sterling silver Victorian Mizpah engraved brooch which i am having difficulties authenticating via the hallmarks. The seller believes it to be SYdenham Brothers dated 1898. Through my own internet research I am not convinced. The Hallmark for the company name is missing the S from S.BROS (this may be because it is such a small item) but the year letter is O and that does not tally with 1898, more like 1888 or 1913 (I hope its the former as the shape of the O is angular). However there is no duty (queens head) mark. If you have any ideas please let me know. Lastly if anyone can identify the flowers on it that would be a bonus!!
Thank you in advance.

Alex
Maltese Cross.jpg

Yes, this is most likely Sydenham Brothers. I note that the initial S is partially visible, but rubbed. That’s what over 100 years of wear and polishing do to silver. The date is indeed 1888. The hallmark cycle from 1875 to 1899 for Birmingham normally had the anchor on its side. Lack of duty mark is not a problem as smaller articles were exempted from duty (I can’t remember off the top of my head what the size limit was).

Thank you Silvermakersmarks, this is great news. I have been reading about duty, and how many items were not stamped. Apparently Arthur Westwood, Assay Master at Birmingham stated in 1922 that 75% of the items Hallmarked at Birmingham were exempt from Hallmarking requirements. Meaning it was mainly done to bump up the value of items stamped. Also as you say the brooch I have shown here is indeed very small too, only 2.7cm by 2.9cm. Either way you have put my mind at ease so thank you, now if only I knew a botanist!