Unfortunately I missed the first half hour of this due to the news [so I've just bought the DVD]. I liked it a lot more than the critics did. I don't think the apology at the end is out of character, I think the boys' reception of it is. I haven't read the Agamemnon for many years, so I don't know if there are relevant details in it, but the use of it without having too many parallels, such as Michael Redgrave's wife really killing him, made it far more universal.
I wrote the above about 10 years ago. I realise upon reading the reviews that précis aren't quite enough to describe this film. The key is to know the story of Agamemnon who "followed the rules" by sacrificing his daughter Iphigenia to Artemis in order to enforce the Trojan War, thereby doubly displaying a lack of humanity. The Browning version given as a gift simultaneously tells Redgrave's character what's wrong with him and reminds him that there was always an alternative path in life.