I also re-edited some other London images that were already on the web site to panoramic which may be of interest to you. I use the 2 to 1 panoramic format rather than anything more extreme. They are all sized to fit a 1 metre by 0.5 metre frame without a border but can be printed to pretty much any size up to this.
More to come!
Tower Bridge from Southwark, near HMS Belfast
Canary Wharf from Rotherhithe
Shad Thames near Tower Bridge