Now saying closing again...
Yes - they're saying that whilst a very limited number of trains have been able to depart, lighting isn't adequate so their closing it again.
http://www.nationalrail.co.uk/service_disruptions/161839.aspx
Just a thought, but don't they have pretty powerful, generator-powered floodlights that would be used for nightime track works fairly handy?
Some lighting has just returned to part of the station, so the next step in the saga could be some sort of further partial reopening for a handful of trains.
You were right...! Highlander at least is starting from Watford Jnc
Right - and then likely to have been wrong - and then right again! Oh dear, one of those threads!
It wouldn't take long for fumes to reach unsatisfactory levels from several tower lights. Sadly those things are not the most environmentally friendly things often having engines that run at 3000rpm instead of 1500 and they are generally only capable of running the lights fastened to them so when they're on they're working at or close to their maximum load.
This (in bold) is part of the problem with trying to implement portable emergency power supplies and/or lighting, especially in a very complex building with lots of different locations with various operational needs - like Euston! The same applies to lots of older / less-well-planned schools, office blocks, control rooms etc. If the redundancy wasn't properly designed for all eventualities, adding extra power supplies and lighting can just add to the problems, as people think the facilities can resume normal operations because some lights are on, but a few crucial bits of the puzzle are often still missing.
Despite what appear to have been exhaustive efforts to work out a way of improving on the emergency lighting, it does appear that Euston simply couldn't cope. Part of the issue with a station environment is, of course, dispatch and the platform/train interface. You can control crowds in selected areas around the concourse, but once it's dark it can be surprisingly hard to safely dispatch a train. I remember one occasion when degraded dispatch of a quiet 8 coach train at a countryside station took me about 10 minutes with manually locking out doors and going back to check nobody was loitering in entrances who could approach the train. Now try Euston in the evening peak, with all its shadows and cubby-holes!