At first glance, I thought it was one of those Ishapore Enfield 2A rifles that Navy Arms modified to Jungle Carbine form , but the magazine is completely wrong and appears to be a standard .303 Enfield Magazine.
The mixed wood precludes this being a Navy Arms rework. I'm wondering if this is just a scratch built cut down Enfield Mk IV. No.1, and is in .303. If it is, somebody did a lot of work on replacing the sights.
This is the carbine made by Gibbs Rifle/ Navy Arms in the mid 1990's from an Ishapore 2 or 2A.
This is an original Jungle Carbine MK. V