Toga is wrong context.
Shawl too informal.
Stole, possibly, sounds rather feminine
Robe, not accurate enough

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Note added at 5 hrs (2008-03-18 07:22:57 GMT)
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Having been educated by "ell", I only retain this here on the grounds that"drape" is more understandable today.

Work round it as best you can! A/c to my dict. , an "aune" is an "Ancienne mesure de longueur, valant environ 1,188m à Paris". Then there's "aunée - Quantité de tissu ayant une aune de longueur".

A yard is close at 1.0936 metres, so maybe "a yard of cloth over his shoulder" would work.

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Note added at 49 mins (2008-03-18 02:19:04 GMT)
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Since they are not Scots or Irish, you can't use "plaid" or "brath", but for the record:

Plaids
A full PLAID may be worn over left shoulder and under right arm, pulled firm to the body. The edge of the plaid should be 11" from the ground at rear of the leg with fringe hanging down below this level. The lower edge of the plaid should be horizontal and parallel with ground. The leading edge of plaid and front face of plaid is secured by plaid brooch high on the left shoulder. While very striking, a full plaid is also very hot, and wrapping and securing it properly requires quite a bit of practice, and generally cannot be done without an assistant. A more common alternative, the fly plaid, may be worn on the left shoulder, usually under the epaulette and pinned with a plaid brooch. The upper edge of brooch should not be above the top of the shoulder, with the design properly aligned. An Irishman might elect to wear a BRATH instead of a fly plaid; essentially the same SQUARE YARD OF CLOTH but folded into a rectangle, draped over the left shoulder, and pinned with a kilmainham (penannular brooch). Plaids are always in the same tartan as the kilt and preferably purchased at the same time, as there can be differences in color from one bolt of cloth to the next, even from the same mill
http://www.reptorproductions.co.uk/music_2/56019.php

A "throw", a "wrap", maybe, if you think it merits the name of an item of clothing as opposed to its length.

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Note added at 7 hrs (2008-03-18 09:28:35 GMT)
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Interestingly, while the "English ell" was 45 inches, the "Flemish ell" was 27 inches.

English ell = 45 in. Scots = 37.2 in. Flemish = 27 in.
http://personal.utulsa.edu/~marc-carlson/history/measure.htm...

This coincides with the "clothyard" of war arrow fame:
The clothyard, or clothier's yard, was a unit of length measure from the times of Medieval England. It was an important unit in that many sources available tell us that it was the commonly accepted length of the arrow used in the British Longbow, a critically important technological and sociological weapon from around the era of the Hundred Years' War. It is fixed in popular culture, as the introductory quote demonstrates, by its use in the tale of Robin Hood, whose arrows were described to be of such length.

Robert E. Kaiser (MA) writes in the Journal of Archer-Antiquaries that the origin of the term clothyard dates to the reign of (King Edward III), who introduced THE FLEMISH WEAVER into England. These weavers, makers of fine cloths which were prized by the nobility, had THEIR OWN UNIT OF MEASURE; THEIR 'YARD' WAS 27.25 INCHES, as opposed to the standard 36 inches. This was the 'clothier's yard.'
http://everything2.com/index.pl?node_id=1471130


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Note added at 8 hrs (2008-03-18 09:32:55 GMT)
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My error! God knows how I did my conversion last night (but it was late ...). A (standard) yard is 91.44 cm. A clothyard or Flemish ell is 68.5 cm.