Fly choice will depend on the time of year. In the spring and autumn weighted tube flies may be required, but if the water is low flies tied on larger doubles or trebles will be sufficient. In summer bring doubles and trebles down to a size 10 or even smaller on some tributaries. On the River Isla for example microtubes with 14 or even size 16 trebles might be all that is required. The most popular patterns nowadays tend to be variations on the shrimp fly theme. A long tail is guaranteed to produce many a longer tale! Your ghillie will advise on the most appropriate patterns.