You're not the first to suggest a Brideshead Revisited comparison, but it isn't really comparable. It certainly isn't too long (127 minutes) and I wouldn't cut anything.

I don't mind long running times if the film justifies it. I've seen 90 minute films that were too long and five hour films that were too short (at least two - Abel Gance's Napoleon which is still missing tons of lost footage, and Lars von Trier's The Kingdom, which technically is a bunch of mini series episodes assembled as a film for wider distribution in cinemas, so perhaps a cheat).