This month I have a shortened Lancaster bayonet for you. The blade has been shortened to 13.6 inches (345 mm) from the original 24.24 inches (621 mm), while the scabbard is 14.5 inches (370 mm) compared to 24.5 inches (625 mm) of the original bayonet. MRD for both is 21mm.
The shorter bayonet is the early type pre 1858 with the shorter locking spring secured by a rivet, while the standard bayonet pictured below is the later type with longer spring secured by a screw.
Apart from a partial inspection mark stamped on the blade it has no marks. According to Ian Skennerton in British & Commonwealth Bayonets, Lancaster bayonets were shortened to 17.4 inches and bushed so as to be used as side arms for the like of the Royal Army Medical Corps.
This shortened Lancaster bayonet is not bushed and will fit a Lancaster Carbine, I wonder if this one was shortened for New Zealand cadets.