I mentioned that the main issue in "regards to
width" was platform edges and didn't mention anything about height
According to Network rail they think they might be able to expand GB+ to the Midland Mainline so perhaps the bridges don't generally fall too victim to this issue...
It definitely seems like they are going through and making gauge improvements as and when they carry out work on infrastructure, such as replacing signals and building new tunnels/alignments. It definitely appears to be a very gradual rate of progress, but one that freight is eager for so there is definitely the incentive to create the conditions needed for bi-level rail cars.
In regards to my retractable step theory, some sort of solution may be needed for "classic compatible" trains on the HS2 network, so that they can use the new platforms as well as existing ones. Anyone got any ideas if a bi-level bid is likely to succeed in regards to HS2 rolling stock, I saw an article on it about a year ago, but not heard anything after that.