[Hamish Young]

To save this running too long..... both Fred and Terry have elements of the answer but not the full answer to each part.
It's important to note that UK records make no distinction between Brown Trout and Ferox

Part 1 - The river system is the Ness, but specifically one of its tributaries the Garry.
Part 2 - The lochs are Garry and Quoich
Part 3 - The 1965 record fish from Loch Garry at 18lb 2 oz was - apparently - the last UK record wild Brown Trout caught on fly 

For those who use Facebook it is worth following the chaps at the Ness District Salmon Fishery Board, Terry mentioned Loch Ness and the Fishery Board staff in conjunction with folk who I can't recall right now, have undertaken some tagging of Ferox in Loch Ness.  Super interesting, if you're a geek like me 

H

[Allan Liddle]

Thanks Hamish, i was going to say Ness but wasn't sure on the tributaries.
Our wild brown trout are certainly interesting to say the least and so much written about them carried through from early years is simply wrong.
We think we know them but in truth we do but no where near fully enough.

[Hamish Young]

We think we know them but in truth we do but no where near fully enough.

That's the interesting thing for me Allan, there's so much been written over the years about Brown Trout but I suspect a very significant proportion of it is supposition based on myth, not fact.
That's what makes some of the WTT projects and other initiatives (such as the Ness Ferox tracking scheme) vital when it comes to improving our understanding of these remarkable and resilient creatures.

Time for another question
I need some thinking juice, which tonight is sponsored by the rather excellent Glenlivet Caribbean Reserve 

[Hamish Young]

From the description, what is the name of the Scottish Loch and what is its unique environment claim to fame

With an average depth of less than 11' this loch is no Loch Ness, yet is also the deepest loch where it is located. It has a unique environment which has been recognised in being designated both a Special Area of Conservation and a Site of Special Scientific Interest. Arguably one of the most bio-diverse environments of its type in Scotland, owing to the unique environment, it is rich in feeding yet the loch it is linked to is more famous as a trout fishing destination.

H

[Terry Coging]

Another intriguing question H.  After much thought and looking at places I am familiar with, realised that although I have fished about 40 lochs over the years I haven't scratched the surface! The question prompted me to look at areas not looked at before such as the Rannock Moor region heading down to Loch Ba. How could I have possibly missed out this region?
Maybe, if I live to 150 I'll learn something 

[Graham Ritchie]

I think this may be the Loch of Stenness, it is brackish, so you can catch both freshwater and seawater species of fish.

[Eddie Sinclair]

Hamish,

Is it Watten?

Eddie

[Terry Coging]

I overlooked Watton because it did not fit the description well, however Lock Scarmclate may? Fished Watton of course but didn't realise that Scarmclate was open to fishing?

[Hamish Young]

The correct answer is indeed the Loch of Stenness To be fair, I made that one a wee bit trickier than the last one, so well done to those who worked it out or knew the answer immediately.
Graham got in there first and importantly mentioned that Stenness is brackish, which was bang on. Its claim to 'fame' is that it's classed as the largest brackish lagoon in the UK.
I only fished it once when I wasn't even in my teens, I have a hankering to go back too as work has taken me past there and Harray a couple of times in the past three years.
H

[Jeff Donovan]

Here's another (excuse me jumping in please), a West of Scotland fly, a proper gem, created in Renfrewshire, the village of Kilmacolm. Used firstly on the river Gryfe then further afield on lochs etc. So, the name of this fly, the originator & his occupation?

[Hamish Young]

Would it be a Dave Downie creation I seem to recall he was based in Renfrewshire.

[Jeff Donovan]

Would it be a Dave Downie creation I seem to recall he was based in Renfrewshire.

Sorry, it isn't one of Dave Downie's Hamish.
A clue; The first part of the name is the most populated city in Texas, the second part is in the original post.

[Jeff Donovan]

Houston Gem?

https://flyfishing-and-flytying.co.uk/blog/view/houston_..._problem_solved/

Spot on, the originator was a Mr James Houston & his occupation was postman.

[Eddie Sinclair]

The Ali McCoist?

[Hamish Young]

From the description, which loch is this

Even with the advent of the North Coast 500, and arguably being one of the lochs of Scotland set in the most dramatic scenery, this remote Highland lochs is seldom disturbed by anyone other than anglers and the occasional deer (ok, maybe sheep too ) having a drink. Like many lochs across the country, in its day it was a truly prodigious Sea Trout fishery, but today is as well known as a Salmon fishery - but it is still one of the better Sea Trout waters we have left.
The short river that runs northwards from loch to the sea is now as famous as its source, incidentally both river and loch hold a good head of decent Brown Trout too.
The loch is a lot easier to get fishing on than the river, yet both are more accessible to anglers (with the necessary means) now than at any point in the past 100 years.
I have never fished it, but did have occasion to visit nearby at a spot overlooking the loch as part of a planning meeting regarding a multi-agency exercise in the location. In short,  it was the second worst midgie experience after the midgie and clegg hell of Loch Ailsh, which this loch is nowhere near.