Trying to give this dubious object every chance, I took a close look at "The Lee Enfield Story" (1993 edition).
On P.56 it turns out that on the trials version of the Lee Metford MkII, the grasping grooves were omitted. Afterwards, in the final MKII pattern the recess under the cut-off handle was also omitted. So a fore-end with grooves but without recess is hard to explain. In my investigation I also took a look at other rifles with grasping grooves - Japanese, Russian
, M1917/P14, but the grasping grooves from a Lee Metford MkI still look like the best fit.
On P.57 is a quote from LOC 6760 "A steel disc (blued) will be employed, instead of the brass disc, in arms issued for drill purposes only...".
Stretching my credulity to the limit, I could just about imagine this rifle as being a "local-brew" bitsa DP rifle. However, not being marked DP but with the dodgy marking on the altered nose-cap spoils even this story...