Alec Guinness did not receive an Oscar nomination, despite receiving a BAFTA nomination, for portraying Major Jock Sinclair in Tunes of Glory.
Alec Guinness was obviously no stranger to playing the military type, having won his Oscar from such a role in The Bridge on the River Kwai. This role in no way repeats that former turn though as Jock Sinclair could not be more different from Colonel Nicholson from that earlier film. This is made abundantly clear from the first scene of the film as Jock and the regiment are partying to sendoff Jock from no longer being the CO. Guinness fashions a Scottish brogue and changes his physical manner in a particularly interesting way to create the Major's personal style. Guinness once again brings a proper quality fitting to a career soldier, in that Jock does have an often stiff posture. There is however a variation in that whenever duty does not call, such as in the opening scene, this is almost lost entirely. He becomes a man who does not mind in the least to indulge in the pleasures of life, bringing a very course quality who fits right in with the rest of the regiment as they drink, smoke, and dance the night away.
Jock finds himself in a strange place as the new commanding officer comes in, Lieutenant Colonel Basil Barrow (John Mills), though Jock is still in the regiment. Jock though had lead the unit during war and it is only in peace that he is replaced. The nature of the replacement offers an interesting challenge for Guinness's performance since simply showing a petulant jealousy wouldn't quite fit the man. Guinness always reinforces that, despite whatever else he might be, he is a soldier who believes in the life of a soldier, however that does not make him a good man or even a great soldier. Guinness performance is very astute in the way he creates a different disregard for his new commander, which isn't so simple. In fact Guinness depicts a genuine humility of sorts in Jock as he apologizes for the rowdiness of the crowd, which Guinness again effectively attaches to the fact that Jock does want to be a good soldier even in this difficult situation.
As the story proceeds Jock begins to undermine Colonel Barrow's authority, and Guinness is terrific in the way he portrays this specific behavior which is not shown in quite the way one would usually expect. He does not show it to be an active disregard for the man, but rather just his instinctual response to the man. There is some sense allowed to Jock for this behavior as he began as just a boy in the regiment and worked his way up to commander through a war before Barrow came. Guinness bring an important honesty in revealing this story as the passion he brings to Jock is pure in this description. The devotion in his eyes, and fierceness of his words place a real sorrow in being displaced, though again he does not break rank exactly. He stays as a soldier and only voices his complaints in a solemn fashion. The problem with Jock ends up being that he's just not a very good man, which basically compels his problematic behavior as a soldier as well.
Jock by nature is a bit of bully and Guinness presents this behavior in a fascinating fashion. It never is depicted by Guinness as an exact malice of the man, rather a innate flaw that relates heavily with a terrible temper. Guinness is excellent in the scenes where Jock interacts with his fully grown daughter (Susannah York) where he is constantly critical of her behavior, and hates instantly any man she has any affection for. Guinness's performance makes this a gut reaction at all times, as Jock can't help himself when his authority is questioned even with his family. This only continues with his interactions with Barrow, which eventually overlap with his daughter when Jock suddenly attacks a soldier who was seeing his daughter. There is only a vicious anger of a brute that Guinness brings to the action, and a lack of any self-control as the way he tries to ignore the issue only proceeds to undermine Barrow as a CO. Guinness is great because he makes the cruelty of the man so subtle, since it is never exactly intentional yet nevertheless is always harmful.
Jock's behavior eventually leads to something horrible that cannot be righted. This brings Guinness's strongest scene of the film as the Major attempts to make up for the wrongs he has committed by suddenly attempting to be the best soldier possible. Guinness is outstanding in this scene as he is so tense in the beginning trying to reveal his perfect plan, and Guinness makes it a especially powerful scene as every second this resolve begins to crumble under the pressure. Guinness is surprisingly moving as he has Jock slowly fall apart as the guilt of his actions overwhelm him. Guinness makes the scene all the more of an impact as he had crafted such a commanding presence and it is properly disconcerting to see the man lose it all in his breakdown. Guinness earns the moment without question and delivers it flawlessly. It's a striking and rather intriguing portrait of a soldier by Guinness. This time being a portrait not of the destruction due to devotion to a soldier's code, but rather the destruction by not truly understanding how to adhere to one.