Well, Christine hasn't done anything, period. So I don't think it's that surprising she hasn't played Mondays at the Canterbury pub or side gigs in London.
secret love: I could actually see that - Christine joining the band for World Turning, Don't Stop, and then adding Everywhere and Songbird.
TimeCastASpell: I completely agree. I loved how the band updated Everywhere for The Dance. I wish they could've used that opportunity to do the same for Little Lies, as I've said a few times in this thread. If Little Lies is performed in London, I would go crazy, as it would be the first time Lindsey has sung the song live. I would want to be there for that.
Here's how certain scenarios might play out:
1. Christine joins the band for World Turning and Don't Stop = As great as it would be for her to be onstage again, I probably would be a little disappointed she didn't offer more.
2. Christine plays those two songs, and adds one other = Probably the most likely scenario. I think that song would be a full-band song: either You Make Loving Fun, Say You Love Me (they did perform this one for the Rock and Roll Hall of Fame Induction, so it means something to the band and Chris), or for the U.K. audience Everywhere.
3. Christine plays the two anthem songs, and adds two encore songs, including one of the songs mentioned above (You Make Loving Fun, Say You Love Me, or Everywhere) and Songbird = This would be great, maybe somewhat likely. I'm still not sure though that Songbird would close the concert in this scenario, because remember this is the Lindsey and Stevie show, they are billed on the ticket and promotional items. I don't think Christine would want to take away from the members touring with her brief presence in the concert.
4. We get a song that catches everyone by surprise in addition to one of the above scenarios: Little Lies, Oh Daddy, or Hold Me = As much as I'd love to hear Little Lies, probably a fool's chance of happening. You guys are crazy if you think she'll perform a pre-Rumours era Fleetwood Mac song.
5. Christine plays the entire concert, adding her voice to classics like The Chain and Dreams, which would finally be complete with her. Several songs of hers are added to the set while others are removed, as secret love indicates above = Well, as great as this would be, I don't think this would happen at all. Imagine how the Internet would explode if it did...eh, that might happen anyway.