Noel Coward did not receive an Oscar nomination for portraying Captain E.V. Kinross in In Which We Serve.
Noel Coward does not just star in the film he also wrote, produced it, and directed it along with David Lean. Coward was actually nominated for producing and writing the film. Coward also plays the role of the Captain of the ship who we see grasping for life on a makeshift life boat, on the ship performing his duties and at home with his loving wife (Celia Johnson). This was undoubtedly a passion project for Coward and obviously his way to show his support for his countrymen in the war that was waging when this film as made. Due to this this film takes a very precise depiction of the men to show them all to be good souls who just want a good life which they sacrifice for the greater good.
Coward's performance is much like his direction and writing here. It's purposefully fairly light in terms of the depth given. Coward portrays the Captain in his home life fairly simply as just a relaxed man who loves his wife and enjoys his life simple as that. Coward brings enough charm, wit and warmth in these scenes always seeming invested enough. Coward seems to frankly give these scenes to Celia Johnson on purpose though, as Coward consistently underplays his role really giving all the emotional moments to Johnson. Obviously the set up was Coward's intention and really it works perfectly fine for the film, even if Coward's performance never becomes all that compelling though.
On the sea Coward is the ship's captain even though Coward physically does not exactly look like a military type. Coward actually offers enough command for the part, and is believable in the role. He also is not overshadowed in the same ways in this scene bringing the needed presence that a Captain should have in such a circumstance. In the scenes of the men trying to survive on the sea without a ship Coward actually is rather could in showing the physical discomfort in the situation and rather effectively loses the usually veneer found in Noel Coward's usual style. Again Coward does not drive especially hard in the role still, he never seems disinterested but always content to be just good enough in the role nothing more.
The one scene where Coward seems to change in this attitude is his last scene where he delivers a passionate speech to his men to fight on and remember the men who died. Coward gives this speech a great deal of passion and you can easily see that the man truly believed these words with all his heart. In that you really see the point of both Coward's performance and the film as a whole. Coward really did not want the acting, or the characters to be the noted thing about the film. No obviously he wanted the message to stand out the most, which makes sense for the time although it makes the film particularly a film of its time only. Coward does not make the other aspects bad though, just very limited and to the point. This includes his performance which is good but ,other than his speech, just good enough.