given this much thought before, but now that you mention it it all does seem very suspicious - the timing, the family connection, the other engagements giving way immediately etc. I think Edward knew that Lucy was coming and that is the reason for his leaving Barton. Either because he didn't want to meet her (who can blame him?) or because he was afraid that she might get suspicious that something was going on between him and Elinor. Even though his behaviour towards Elinor is more reserved than it was at Norland, Lucy might still detect a something there.