Found this in Surgeon Haddy James' journal about his time in Paris in late 1815:

The Prussian soldiers, who with the English are the most commonly seen in Paris, are exceedingly neatly dressed. Their coats
are blue, dark brown or dark green, with trousers of dark brown or green with stripes. The uniform of the officers is particularly
well made, and I think they must frequently wear stays. The ornaments are very handsome. There is little difference between the
dress of the infantry and cavalry. You never see a Prussian officer without his sword by his side, for they never will trust the good
will of the Parisians.
Although the colours are the same, it is never difficult to distinguish a Prussian from a French officer by the cut of his uniform,
and there certainly could be no mistake about the face. The Prussians are almost invariably fair, with large broad faces, and light
hair and mustachios.
The Russians that are in Paris are a fine race of men, broad faced and hard featured. It was not always easy to distinguish
them from the Prussians. The Cossacks in Paris have short red jackets with those immense trousers which go by their name.
They wear their hair straight and thick like the statues of the old Kings of France, whereas most of the Continental nations wear it
long, and consider it a beauty to brush it up in every direction, so as to make their heads, at all times large enough, of enormous
size.
In August there was a review of the advanced guard of the Russian Army, amounting to about eighteen thousand men, infantry,
cavalry and artillery. We understood that they did not all of them belong to the Guard, but they were probably all choice
troops, and they were most certainly of a very superior description. The infantry were clothed in green with white trousers and
cloaks crossed over the back and chest. The greater number of the front rank wore medals suspended by a light blue ribbon. The
Grenadiers wore long black feathers, and the cavalry were all Cuirassiers, and were dressed in a white jacket and green trousers.
The cuirasses were partly black, partly brass and partly steel. All those of the latter kind were taken from the French during their
retreat from Moscow. The men are fine stout fellows of a very military aspect; in point of horses and appointments, however,
they appear inferior to the British Heavy Cavalry. They all wore black helmets with crests curving forwards of split whale-bone,
or something of that kind. The artillery, both horse and foot, were inferior in their appointments to the English, and their guns very
heavy, for the most part nine or twelve pounders. The dress of regimental officers in the Russian service is very plain; that of the
field officers very handsome. Taking this as merely one corps of the Russian Army, it must be allowed that in point of size it is
superior to any corps in the English service.
The dress of the Austrians is white with tight pantaloons of light blue, often embroidered. The Hungarian Grenadiers are
those principally in Paris, and bear a most military appearance. The dark moustaches which they all wear appear to great advantage
on the dark and swarthy faces, and look much better than the light or red hair which appears on the lips of their northern neighbours.
They wear Grenadier fur caps, like those on the heads of the Scots Greys.
The Bavarians are in sky blue. The Nassau troops, in bottle green faced with orange, broad Grenadier caps, or caps with
orange feathers, are the finest-looking body of men in the Duke of Wellington's Army.
The Belgians wear blue faced with orange; the Brunswickers black with sable plumes, and the death's head and crossbones on
their caps.
The Hanoverians came, with the other subjects of our most glorious Sovereign, clad in scarlet, with the 'G.R.' on their caps,
but yellow sashes round their waists. They are frequently singing German hymns or airs, as is the custom throughout this warlike
Empire, from the Tyrolese hymn of Liberty and the Hungarian Waltz to the Teutonic hymns of the northern Germans.
The English infantry, with their little caps, badly made jackets and dirty grey trousers, certainly do not bear the prize in point of
appearance. But their steady march and determined air are such as can never be looked at with indifference, and as the Highland
regiments sweep along with their bagpipes, their bonnets and their swinging kilts, there are none of the Allied sovereigns or
generals but would do homage to the bearing of the 'Sans Culottes'.

The general tattiness of the British Army in Paris at this time is found in several sources, but his comments about the Russians and Nassau troops in particular are interesting;
also the Prussian troops having dark brown or dark green trousers. Having the 'GR' badge on the Hanoverian's caps suggest most were wearing shakos rather than Prussian-style Landwehr caps.

Steve Brown