[Derek Roxborough]

 So then which one would it be? remember the Romans were supposed to have used a red wool body and a feather from a cockerels neck , essentially a red palmer, no mention of any other fly. choice of 3 materials So, What would keep your interest up?. Derek Roxborough

[Terry Coging]

The 'one' fly for me would be the Montana nymph. Hugely versatile.

[Dave Robb]

If we’re talking trout, it surely has to be a pheasant tail nymph as the best all rounder?

I really can’t think of another pattern where it almost comes with a guarantee.  Rivers, lochs, fisheries, it does the business everywhere.

I do like a Black Pennel though and that would be a close second.

[Liam Stephen]

Ptn! 

[Derek Roxborough]

 I've caught more on a Black pennel than I ever have on a PTN, Derek Roxborough

[Derek Mckay]

Ptn here as well.

[Bryan Redd]

I've caught more on a Black pennel than I ever have on a PTN, Derek Roxborough

Derek,  Do you fish the Black Pennel only in  stillwaters, or in rivers too?

Cheers,

Bryan

[Derek Roxborough]

 I am essentially a loch fisher, very rarely get the chance to fish rivers , although I caught trout in the Tirry on a Zulu,    Derek Roxborough

[Eddie Sinclair]

Hares lug

[Derek Roxborough]

 thinking about it , and being a wet fly fisher, it would have to be a Solwick, Derek Roxborough

[James Laraway]

for me the choice would come down to 2 flies...

a close second would be a gold head hare's ear nymph

...wait for it....

 first choice would be a humungous ( preferably black with orange dumbell eyes) !

Why ? They will catch browns and 'bows. Stocked and wild. Will tempt trout from big to small in rivers and lochs - and all the way through the season...

none of the namby-pampy stuff for me...

[Rob Brownfield]

Define "one fly"

I would choose a PTN because I can dress it small, large, long, short, with beads, without beads, with hot spots, with sparkle, with a wing and more.

Is that still "one fly"?

I have them large to represent stoneflies, but also with a pearly thorax that, when stripped, looks like a minnow. I have them dressed with a CDC plume to act as an emerger, I have them ties curved to look like a buzzer, of course I have beads to get them down in the river....the list is endless.

[Sandy Nelson]

Would have to admit to the PTN as well. 

Never been my favourite fly by a long way, but if i had to eat...............

Sandy

[Allan Liddle]

I struggle with one box, never mind one flee

Ok then, maybe DHE, or Dirty Duster, or PearlyHE, or Cow Dung Hopper, Nope it would have to be a Hedgehog, or a Half-hog Hopper, then there''s the Black Nymph, Rubber legged jig, oh French Nymph, PTN, farkit i'll just take the box and decide when i get there 

[Liam Stephen]

Allan yours is the squirmy I thought?