I have purchased a permit this season for the River Devon, its not expensive and covers this small river from the Menstrie/Tullibody bridge right up to the Castlehill Reservoir above Muckhart. Permits are available at Stirling Angling Centre amongst other retailers that can be found on the Devon Angling Association website. Two season permits are available, a Brown Trout permit, and a Salmon/Sea trout permit (that also allows for Brown Trout fishing). Sea Trout and Salmon fishing is limited to the lower river up to 1/3 of a Mile below Cauldron Linn between Vicars Bridge and Rumbling Bridge.
2011 prices for a brown trout season permit is only £17.
As the permit comes with a hand drawn not to scale map I have put a Google map together showing the main points marked on the beat maps. Its not exact in all places as I am not that familiar with the river yet so some points are approximate- check when you are on the ground.
Check out the River Devon Angling Association website for more detail.
View River Devon in a larger map