Going slightly more on-topic, with regards to the 387's from Gatwick Express going to GN, if hypothetically things were to magically improve and GatEx returns, would those missing 6 units have a detrimental effect to the service? As much as we seem to think GX isn't needed, it is (as someone else pointed out) up to DfT and the airport to decide that, and most likely it will be back in some form. Would this move-over be a permanent measure?
There was a rumour that GN would get 379s to replace 365s, but that seems to have changed to the 6 c2c 387s along with 6 GX 387s. This would mean no Driver Conversion costs, and multiple working without any adaptation - so fewer spare units needed in comparison as only one fleet, and also intense and less intense diagrams would be balanced out amongst all the members of a larger fleet.
A reduction in travel generally could be absorbed across GN, GX, and c2c in the medium term.
In the long term, there would still be 30 379s available to go somewhere should passenger numbers pick up.
Could the software on them be changed so that multiple running with 387s could take place (upto 100mph. 387s only run at upto 100mph on the GN presently anyway)?
Could third rail shoes be fitted to them?
I don't think it would be too much hard work for either of those things to happen to broaden the options available, North or South of the river, but the apparent current plan of the 6 GX and 6 c2c 387 units seems sensible.