The first example above is the Campbell tartan, often sold as "Ancient Campbell" by vendors. It is the same sett, although in a lighter shade, as Black Watch, a regiment raised by the Duke of Argyll in 1739. All Campbells and septs may wear this sett.
   Look carefully, and note that it is a double sett. This means that it takes twice the distance to repeat the pattern as a single sett, or a basic square pattern. Look at the double tramlines, pairs of narrow black lines like railroad tracks. Moving across the tartan left to right, there is one double tramline in an area of blue, an area of green with a single line, an area of blue with two double tramlines, followed by an area of green with a single line. This completes the pattern, which is the same up and down as it is across.
   Hues may vary according to preference, as long as the colors are blue, black and green. Color schemes sold by the mills are usually called "ancient" and "modern." These indicate a lighter shade for "ancient" tartans, purported to represent the lighter coloring of the older, traditional, methods of dying the wool. The "modern" tartans are darker, with blues appearing to be verging on purple. So, if one chose to wear a lighter shade of Campbell tartan, one would order a kilt made of Ancient Campbell tartan in the "ancient" color scheme.
   This tartan is worn by Campbells originating in Argyll, as well as any other member of Clan Campbell. This is the main tartan of the clan, and may be worn by all Campbells and those with Clan Campbell sept names.

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The message below is from the CCSNA Website

OFFICIAL POSITION ON CLAN CAMPBELL TARTANS

Many a Campbell and member of a Campbell sept has sought the answer to that question upon first becoming interested in his or her Scottish heritage. Unfortunately, many have looked to the wrong sources for the answer--namely, to merchants selling tartan goods. There is only one authority on the correct tartan or tartans of a clan: the chief of that clan. Not even the Scottish Tartans Society or the Lord Lyon King of Arms claim such authority--they are purely archivists of tartan history, which is, at best, a confused and confusing field.

Here is how our late chief, the 12th Duke of Argyll, and re-affirmed by our current Chief, the 13th Duke of Argyll, Mac Cailein Mòr, summed up the official position on Campbell tartans consistently declared for nearly two centuries by successive Chiefs of Clan Campbell:

 

 

"...the only tartans which I recognize are, firstly, the one you see me and my wife wearing, which goes under various names, such as ordinary Campbell, Ancient Campbell, etc., and all members of our clan who are not specifically identified with [the Houses of] Breadalbane, Cawdor [or] Loudoun are entitled to wear it.

Let me get rid, once and for all, of the thought that there is a 'Campbell of Argyll' [tartan]. While it is true that the Sixth Duke [of Argyll - b.1768 - s.1806 - d.1839] introduced a white line to his plain Campbell tartan to differentiate himself from the rest of the Campbells, (he being the chief and entitled to do so), he was the only member of the family so to do and the rest of the family thought he was rather pompous to do it.

Campbell of Breadalbane--fine [to wear].

Campbell of Cawdor--fine.

Campbell of Loudoun--fine.

Campbell of Glenlyon--I have never heard of it.

Campbell of Loch Awe-this is plain ridiculous, as we are all Campbells of Loch Awe originally. - Apart from anything else, I have never heard of a Campbell of Loch Awe tartan, nor do I wish to do so.

THERE IS NO DRESS CAMPBELL [TARTAN]--repeat! repeat! repeat!

There is NO HUNTING CAMPBELL.

There is NO CAMPRELL RED.

There is NO CAMPBELL - SIMPSON.

There are no Campbell cheques, other than commercial ones...

If I feel strongly about anything and would like it inscribed on my tombstone, there might be a few lines such as 'All Campbells with the exception of the three principal septs [the Houses of Breadalbane, Cawdor and Loudoun] should wear plain undifferentiated Campbell for evermore and not get confused by peddlers of this [other] material that comes under all sorts of guises.

Yours ever,
Your Kinsman and Chief,
Argyll"

[From a letter to the late William A. Mitchell, Clan Campbell Society, U.S.A. genealogist.]