These are the first four verses of the Carthy version.  The first refrain line is, I think, meaningless; I've rendered it as close as I can to the sound, but others may be able to get closer.  So far I am defeated by the first line of verse two!

Lady Margaret she sits in her bower sewing
Ba-ba and a lily-ba
When she saw the knight with his horn a-blowing
On the very first morning of May.

"Oh (ought oh ought)?? would give to me rest
And* that young knight lay here on my breast."

Now the lady she had these words scarce spoken
When in at her window the knight come a-jumping.

"Oh, strange it is, oh strange, young woman
I can scarce blow my horn since I heard you a-calling."

* In the old sense, probably, meaning "If".

After this we get to the usual sequence:

Go get me gold... etc.

I don't know about C'est l'Aviron, (though I'd be very surprised if "M'en revenant de" meant anything other than "While I was coming back from") but The Outlandish Knight is certainly well-known in France (as in a number of countries, of course) where it is usually called Le Tueur de Femmes. Now that I've mentioned it, I just have to post the thing...

LE TUEUR DE FEMMES

"Allons, la belle, nous promener,
En attendant le déjeuner.
Allons, la belle, allons-y donc:
'Y a du plaisir nous promenant."

Ils ne furent pas à mi-chemin:
"Mon Dieu, Renaud, que j'ai grand faim!"
"Mangez, la belle, votre main,
Jamais ne mangerez de pain."

Ils ne furent pas au bord du bois:
"Mon Dieu, Renaud, que j'ai grand soif!"
"Buvez, la belle, votre sang,
Jamais ne boirez de vin blanc."

Et quand la belle fut promenée,
Elle demanda-t-à se loger.
Tu logeras dans le vivier,
Ou j'ai sept femmes de noyées."

Et quand ils furent au bord du vivier,
Lui dit de se déshabiller:
La belle ôta son blanc jupon
Pour aller voir la mer à fond.

"C'est pas à toi, franc chevalier,
De voir ta mie déshabiller.
Mets ton épée dessous tes pieds
Et tourne-toi vers le vivier."

Elle l'a pris, l'a embrassé,
Dans la rivière elle l'a jeté:
"Pêche, Renaud, pêche poisson;
Si tu y en prends, en mangerons!"

Quand le beau galant fut à l'eau,
Il se raccroche à une branche;
La belle tira son grand couteau,
Coupa la branche au ras des flots.

"Voici les clefs de mon château;
La belle, je vous les donnerez."
"Je m'soucie autant de tes clefs
Que je me soucie de toi*."

"La belle, qui vous ramenera
Vers le château de votre père?"
"Le cheval qui nous amena
Bien doucement m'y ramenera."

"Mais que diront tous vos parents
De vous voir revenir seulette?"
"Je leur dirai la vérité;
Que tu as voulu me noyer!"

* pronounced the old way, to rhyme with clefs.

This version, from the Ile de France, was recorded by Jean-Francois Dutertre on L'Epinette Des Vosges (Chant du Monde LDX 74536, 1974).  The song has sometimes been found as a second part to La Fille au Roi Louis, and it is from one of these -probably the version printed in Henri Davenson's Livre des Chansons, that Dutertre got his melody.  I'll send a .midi to the midi site.  Davenson also gives a (very similar) version, but with a far less interesting tune.

"Let us go out riding, fair maid, while we wait for the midday meal.  Let us go, fair maid, let us go, then; there is pleasure in going out riding."
They were scarcely half way along the road: "My God, Renaud, I am very hungry!"  "Eat your own hand, fair maid: you will never (again) eat bread."
They were scarcely at the edge of the wood:  "My God, Renaud, I am very thirsty!" "Drink your own blood, fair maid; you will never (again) drink white wine."
And when the fair maid had taken her ride, she asked to go home.  "Your home shall be in the pond*, where I have seven drowned wives."
And when they were on the edge of the pond, he told her to undress.  The fair maid took off her white petticoat, to go and see the bottom of the sea.
"It's not for you, bold knight, to see your sweetheart undress; put your sword beneath your feet, and turn towards the pond."
She has taken hold of him, put her arms around him; into the river she has thrown him.  "Go fishing, Renaud: if you catch anything there, we will eat it!"
When the handsome young man was in the water, he catches hold of a branch.  The fair maid pulled out his** big knife (and) cut off the branch, level with the waves.
"Here are the keys to my castle; I shall give them to you, fair maid."  "I care as much for your keys as I do for you."
"Fair maid, who will take you back to your father's castle?"  "The horse that brought us here will take me back gently enough."
"But what will your family say when you return all alone?"  "I shall tell them the truth: that you tried to drown me!"

* literally, an expanse of water where fish are bred.

** or "her", assuming she had one!

Malcolm