The book Adam is seen reading over breakfast (in an orange-covered Penguin paperback edition) is "Brideshead Revisited" (1948), by Evelyn Waugh. This is significant - Adam's unlikely friendship with the very upper-class Catholic, Donald, parallels the friendship between Charles Ryder and Sebastian Flyte in Waugh's novel, and in both stories the more aristocratic friend is doomed.
At one point, Adam Morris speaks in a funny voice - he is imitating "Bluebottle", an eccentric character in the legendary radio comedy series "The Goon Show", where he was voiced by Peter Sellers. Sellers always maintained that the odd voice was based on that of a real person, a scoutmaster he had once met.
At 9 mins 40 seconds, boom mic appears at top right corner of shot