Mikey;
Brown trout are THE hardest fish to catch ..any seasoned anglar will tell you that. The lateral vision of these fish are incredible. You really need to snaek up on these guys,especially in the tribs.
In the rivers usally you would cast lures up stream ; and with a fast retreive and sudden stops, you may have a chance.
But YES you are correct, the most effective way of getting these critters would be the fly. If you are not a fly fisherman, then a small jig/weighted fly under a float may work for you, Use a long mono leader 5' or more and a clear float.
If you're not getting them, dont feel bad, they are damn near impossible to target, usually a landed Brown is a pleasant surprise for a guy trying for bows! For me so far anyway, they are one smart fish!!
Tight Lines, Hopes this helps a wee bit.