It's funny, because I've read and reread this novel so many times that it's hard to recall my earliest impressions of it, yet I don't think I ever believed that hair was Elinor's!

The introduction to the Broadview edition has quite a lengthy section on this supposed 'theft' of Elinor's hair. Kathleen James-Cavan links the whole incident to the earlier comment made by Elinor to Marianne about 'admiring Pope no more than is proper' and suggests that Elinor may have an "inordinate admiration for Pope's The Rape of the Lock".

The poem, as I mentioned earlier, is a satire (supposedly based on a true incident) of a gentleman stealing a lock of hair of a lady and how much was made of the whole affair, as though it was a very serious offense. In fact it is called a 'dire offense' in the first line of the poem, and Pope goes on to write of 'black omens' and 'dire disaster' as the event approaches. It's a little hard to keep a straight face with lines like these:

For ever curs'd be this detested Day,
Which snatch'd my best, my fav'rite Curl away!

James-Cavan sees Elinor as having invented a whole little tale for herself about how Edward must have taken the hair from her. She says that this behaviour is "inconsistent" with the Elinor whose understanding and coolness of judgement we have so far come to admire in the story.

According to this intro., Elinor has cast herself in the 'Belinda' role (the one whose hair was stolen) of The Rape of the Lock. "She is so eager for evidence of Edward's attachment to her that she invokes Pope's poem." However, what Elinor forgets is that in the poem, the Baron who stole the lock really only wanted to possess the lock of hair and did not intend it as proof of his feelings for Belinda. The fiction Elinor has invented for herself, according to James-Cavan, "grants her the authority she needs to deceive herself about the proofs of Edward's affection".