the look of a condemned spinster

They can do the most amazing things with makeup and lighting. Compare Olivia de Havilland, Joan Fontaine's sister, in her roles in Robin Hood and Gone With the Wind. As Marion, de Havilland is unbelievably gorgeous. As Melanie Wilkes, well, plain would be the kindest adjective that comes to mind.

http://thinkingoutloud-descartes.blogspot.com/

While I understand the concerns expressed above in this thread, I think it would be helpful to consider some of the contextual elements very much provided by the film to make this transition as it were more understandable.

First of all I am not so sure Lina's relatively less vivacious appearance when we first see her, in the train, was meant to be seen as literally unattractive. She was dressed conservatively, wore glasses and a hat (inside) that all added up to make her something other than the gorgeous woman we see her as later.

But that is not the same as saying she was literally unattractive, or even plain. After all Johnny does take note of her, and not just to mooch a stamp off of her.

It is true that in the next scene when he sees Lina on her horse that he says "That can't be the same woman!" But of course what he is really saying is that it very well is the same woman, and he is intrigued to say the least.

I take this to mean rather than the film submitting that Lina is literally plain, that she (at least in the earliest scene) CHOSE to present herself with a withdrawn, even uninviting, appearance.

Before returning to the foregoing thought, another element of the context here is that Johnny refers during the scene when he and the (I think it is the)Barham women come by Lina's house on the way to church, he says something which strongly implies there are not many attractive single men in the area. Later we see a fellow named Reggie ask Lina to dance, and they clearly are not a match made in Heaven. So there is Lina, living at home with mom and dad, no obvious candidates around her, and her parents overheard talking about her lack of prospects.

Now of course the film does not provide any backstory for why Lina is living with her parents, whether she had previous lovers, to what extent she may have chosen to withdrwaw from the world, and why. Nothing along those lines is even implicitly referred to. But it is fair to say there must be something. Let me put it this way - it is not necessary to understand the film as saying Lina literally arrived at her station and age in life never having "lived" as it were. All we need understand is that there is some risk that if she went on as she was living, at a remove from the world and no suitors around, even a NOT plain woman like her might be "risking" a life as what was referred to not long ago as an old maid.

Could she have moved to London or some other city? Why not? But she had not, and very well probably had her reasons for living at home. If on the other hand single men were literally "around", are we supposed to assume none would see Lina for who she really was? Of course not.

Introduce Johnny into her life, and I think it is not merely desperation triggered by overhearing her parents. She is at first reluctant to take a chance on Johnny, and then completely changes her mind. Because she finds him attractive.

Well, as the saying goes, changing her mind is a woman's perogative.

In short, the transformation makes sense to me. It is better understood in terms of the film's context than in some comparison of Olivia de Havilland's role in GWTW to some otehr of her roles, or for that matter to Joan's own work in Jane Eyre.