I have always wondered why UA doesn’t promote this for their LHR operations. T2B would be relatively easy to adapt by putting an overhead concourse above the northern end, which would allow built in flexibility for US/non-US departures.

This would make a lot of sense for their US connecting business and they already funnel much of the European connections through FRA, MUC and ZRH. Having said that, many of their better customers would have GE so would not benefit.