I'm not 100% sure because I'm more familar with the Series 3 ex Mil 109s, but with extended spring shackles and so on, it appears to be what it purports to be. The photos need to be a bit clearer ideally to get a good view.
Being a late 2A Ex MOD 109, I think it has the wrong rear cross member fitted, but I don't actually know when the UK MOD went over to the square rear cross member. I might stand corrected, but I thought this was in the 2A era and earlier than yours.
It looks as though it has had quite a lot of welding which is to be expected at this stage, but can you find the chassis number stamped on the RHF chassis leg? Given that you may have some issues with getting a V5C for this vehicle, correct identification of a stamped chassis number actually on the frame will be essential to satisfy DVLA. I think that they may not accept just the bulkhead screw on plates.
Looks like quite a nice and relatively original vehicle. All I would urge, as others have done, is to be very wary of buying anything without paperwork. Ask yourself why it does not have a V5C, because if you can't get it registered on an age related plate and it ends up on a Q plate, that will signifiantly impact on its value. Again as others have said, do talk to the S2C Vehicle Registration Officer. He may be able to save you a whole world of pain...