I had stopped off to eat some lunch in my car after a meeting, and I was alongside the west coast mainline. There were plenty of trains zipping up and down the track as I ate and I did take a few images while I relaxed. Only as I looked through the images when I was back at home, and I zoomed in to see which images were sharp did I notice the tracking of the pantograph along the overhead wire. The upward pressure was deflecting the wire by varying amounts depending on where it was in relation to the supports. It is interesting how much it can move the wire when passing so swiftly.