Dorothy, the "circle L" means that the lens is Lumenized, i.e., hard coated. That's all the coating Kodak offered and its more than is needed on tessar type lenses like your Ektar.
I didn't see flare in the sample you posted, I saw blown-out highlights and a very contrasty print. If flare had been a problem, you wouldn't have so much contrast.
You should probably unscrew your lens' cells from the shutter and clean the accessible surfaces. Mold should not be left to grow.
When you're done the rear cell, which contains a cemented doublet, should be crystal clear. If it isn't, time for a new lens. The front cell contains two singlets and basically can't be opened for cleaning the interior surfaces. If there's crude inside it, time for a new lens.
I have two 101/4.5 Ektars, much the same lens as yours but shorter; one coated, the other not. The uncoated one shoots better and neither has flare problems. But, when I make the effort I can take shots like yours with the uncoated one. The difference between mine and yours is that I rarely underexpose the background so much. How did you meter that shot?