There is not nearly enough information to form a proper conclusion.
A mismatched bolt on a Lee-Enfield is a VERY SERIOUS problem form a collector's point of view and would break most possible sales deals, both now and in the future. The chance of finding the original bolt is EXTREMELY slim. Milsurps.com has a thread set up by ~Angel~'s "Match Making" Service for "rifles looking for bolts." https://www.milsurps.com/showthread.php?t=1035 A mismatched Lee-Enfield bolt will ALWAYS hurt a deal. If selling the rifle to a re-enactor or shooter, it might not matter as much, but even they would not want to pay a top dollar.
The lack of a scope serial number on the butt just below the cocking piece, tells me that this is ALMOST CERTAINLY a No. 4 Mk. I (T. LESS TELESCOPE) which was NOT a sniper rifle as it was an unfinished conversion in that it never had a telescope and bracket fitted in service. Such a rifle would usually have "TR", "S" and "S51" markings. If that is the case there should be no "T" on the left side, no scope number on the butt (as noted) and the rifle serial number on the bracket would be for a different rifle.
We do not know all the reasons why there were so many No. 4 Mk. I (T. LESS TELESCOPE) rifles made. Many of these were early Stevens-Savage production and some were late-war BSA Shirley production. The late-war examples are understandable, for the contract ended on a specific date, so regardless of how many rifles were partway through the conversion process, it was a case of "down tools" at the appointed hour. (Info from Peter Laidleras I recall).
I disagree, most respectfully, with "breakeyp" in that I have never seen any indication that the cheek rests were only fitted after issue to snipers. The one exception is that the very first No. 4 Mk. I (T) rifles were reportedly issued without cheek rests, but these were fitted as soon as they became available.
For American Garand collectors, they can identify with this unfinished sniper conversion situation by thinking of the "SA-52" marked M1rifles. Drilled for the M1C scope base, 4,796 unfinished M1C receivers had the special scope mount holes plugged and the rifles were issued in the Korean War as standard M1 rifles, marked SA-52. As a result, they are not and were not, technically snipers as the conversion was never completed. [Ref: The M1 Garand Rifle - Bruce N. Canfield p. 526]