Thanks, Jim,
Unfortunately I don't have an Ancestry sub. However the TNA link you provided is the faulty one which links to the 22 Field Ambulance Diaries (with the pdf names WO95/167/2_1 etc). I assume the ones on Ancestry are the correct ones (pdfs WO95/2944/2_1 etc). The important thing is that it appears that Louise has the Ancestry link so she can access the information she needs.
Louise, the diary entries should be signed by the CO at the end of each year so you should be able to confirm that Lt Col GA Harding RAMC is the commanding officer.