The Sparkbrook works was actually originally owned by the National Arms and Ammunition company who negotiated into the Military Martini contracts for the war office in 1878 to supply 33% of the contract. BSA had 40%, NAA 33% and LSA 27%. They went bust on December 20th 1882 after only producing around 10,000 Martinis. The Government purchased the works in 1884 to extend the repair capabilities but also to manufacture the new Enfield Martini .402 arm, which was cancelled in June 1887, after that it converted most of the 70,000 rifles made in .402 into Martini Henry MkIV's. The men browning the barrels and actions are browning MkIV rifles.
The works began full production of Magazine Lee Metford .303 in 1889 and the barrels you can see look like Lee Metford furthest away, the Lewes fore-sights give them away. the middle are MH. Nice images, I have some of them for my book.