In K.C. Jones compendium on Birmingham maker's is mentioned (p. 308) only Bishton Ltd. - their mark registered in March 1945, with other frame and content - was founded in 1889 by Thomas Bishton. There is no mark shown belonging to Bishton & Fletcher. Well it could be that this 1981 published compendium - all (!) Assay Office files were used - wasn't/isn't the almost sounded research on Birmingham maker's mark?
Bishton Ltd. is there (p. 308) described as a «bullion dealer».
Enlarged shown maker's mark - I think - is that of «Betts & Fairfax» (p. 327, 1st vert. row of marks).
Date later, «user701» already mention to, IS x = 1897(p. 382); and not r = 1891 (p. 382), because - already mentioned to by «user701» - r is in a vertical oval frame = and that isn't the case shown here.
To know for sure which maker is involved here, it is necessary to study product range of these two mentioned company - but where?
Kind regards silverport