We think LU are being a bit disingenuous about this. Trains may have been running on the Northern Line but plenty of stations were closed, as we ourselves found out at Charing Cross. The Guardian comments section contains tales of trains leaping between Waterloo and Tottenham Court Road and closed stations on the District line (large sections of which were touted as open on TfL's site). Perhaps 40% of trains were running, but LU might get more sympathy if they were up front about the whole situation.
Anyone who has ever tried to coax a crumpled £5 note or a newly minted coin into a ticket machine, or been overcharged on an Oyster card, will know that [LU MD Mike Brown's] bland assurance that "Staff will still help with any problems" is meaningless at a station where the ticket office is closed.
Good point, well made?