Pheasant Tail variants or Hare and Copper (sizes 16 or even smaller when river is very clear and low) work well.
Greenwell's Glory, Coch-y-Bondhu, Adams, Kakahi Queen, beetle patterns (in early summer) and cicada patterns (from mid summer) during the day and Twilight Beauty and Dad's Favourite for the evening rise. Fish will often be seen rising during the day but require very delicate and accurate casting to fool them.
Greenwell's Glory, Grouse and Purple and Red Tipped Govenor fished sub-surface work well, especially in the evening.
Spinners: Small bladed spinners such as Mepps or Veltic.