Had some success at the weekend on this one tied as i will show

.....this is one that caught the most and has worked for me before.
Size 12
Well i was getting refusals to the above one so ive tied some smaller which i think are more the size of fly that was on the water
Hook; size 14 short shank
Body; large black cock hackle
Wing; crystal hair
Hackle; black cock
Wind thread halfway on hook
Take large black cock hackle from back of cape and tye in
Wind hackle to back of hook and back to thread and catch of
Pull the hackle fibers forward and catch with thread
Trim waste and tye down with thread
Take a single strand of crystal hair and fold twice to form 2 loops
Then tye in
Then add black hackle
Wind on as normal and job done
A bit smaller than one i was using at weekend and may have caught more,not that im complaining
Well there you go try it in both sizes i know i will
Cheers,
Geordie.