Thanks for the response. I'm not sure though that the lights (apparently they're called "Belisha beacons"?) were there in 1969; I think they're there now to warn drivers about the busy crossing (busy, of course, because so many people visit to try to recreate the album cover!).
Furthermore, I'm prepared to say now that it's a total load of rubbish that the crossing has been moved. For different photographic proof, take a look at this photo, purported to have been taken by Linda McCartney. The Beatles here are poised to cross back "the other way". You can see the sidewalk starting to curve away just at the end of the crossing. Compare this to the aerial view on Google Maps, or even the live webcam at
www.abbeyroad.com/visit/ (the webcam is pointing in the opposite direction from the famous photo), and you'll see that it's exactly the same now.
