The Organisation des villes du patrimoine mondial (Organization of World Heritage Cities), of which Québec is a member (and which is also the headquarters), also a flag of its own (since 1995): (the pictures aren't good, however)
Attached is my attempt at reproducing the flag from the images on the site. It looks like the proportions are definitely 2:1, with an oval occupying approximately 62% of the (white) field vertically by 70% horizontally. The oval is of such thickness that the inner edge is approximately 70% vertically by 80% horizontally (of the outer ellipse). The three bars superposed on it (and creating a gap at the oval's base) seem to be dark red on top and dark gold below.
I recently saw a colour poster by the Organization of World Heritage Cities, and I was able to check on the design and colours of the logo (it measured 2,5 x 1,25 cm). I can report the oval has proportions of 2:1, and the colour a very dark greenish blue (~RGB 0, 56, 64).