] Did the Colonel have any idea about Darcy's feelings for Lizzy. I doubt they would have spoke about it but could the Colonel have noticed something in Darcy's behaviour? This could be a further reason for him to back off.

Charlotte couldn't find anything in Darcy's behavior that indicated his feelings for Lizzy, and she very much wanted to. Of course, the colonel knew his cousin better than Charlotte did, so it's hard to say.

] Surely he could not be that poor that he could have no chance to marry her. Mrs Bennet mentions earlier Colonels earned 5,000 pounds a year (I keep in mind that Mrs Bennet has a tendency to exaggerate so this sum might be unrealistic) and though her may have no fortune surely this would be enough to live off. He could then be backing off to let Darcy pursue her - and this would of course, be a very amiable thing to do.

Where do you get the figure of 5000 pounds a year? I searched the novel and couldn't find what you were referring to. If he had an income like that, he probably could have married where he chose. It sounds terribly high for a colonel, though -- the same as Bingley makes and Bingley's income had Mrs. Bennet swooning. I think his pleading of (relative) poverty was sincere.

] I think also that the Colonels attentions function to make Lizzy seem more sought after. Though it's never said, she appears the sort of girl that attracts many men. Although she is openly pursued by two men I get the impression there are plently of men who also would if they had the means to.

I don't really see her that way. I think of her more as an acquired taste. I don't think she fits the beauty conventions of the day, and there were no doubt a lot of men who would not have wanted such an outspoken wife.

] I think by adding this situation with the Colonel suggests that Darcy is certainly not the first to appreciate and fall for her (which appears to be so at first glance). There is a moment in P&P2 where this is also made clear. When Lizzy is talking to Denny when she arrives at the ball her sisters come and drag him away. A young officer akwardly apologies to Lizzy for not being able to dance with both her sisters and bows deeply to her as he leaves. This interlude perfectly sums up desirablility. I think all this makes Lizzy's love for Darcy of more value - that many men (and not all of them foolish and unattractive) have pursued her and none of them have made her fall in love.

I don't see Lizzy as being pursued by many men. There are no mentions of serious possiblities (though one is mentioned for Jane), and I don't think she had the sorts of looks that turned heads at first glance. She is not, as I said, conventionally attractive by the standards of the day, and even Darcy has to study her for a while before he finds anything attractive about her. His first impression, even after studying her, is that she is "tolerable," and after studying her a little longer that she didn't have a good feature in her face. It takes him a while to change his mind.