Winckworth Sherwood was so concerned that its lawyers would ignore a terrorist alert in order to hit their billing targets that it used its emergency communications system to tell them an extra day would be added the following week.
The firm's office, Minerva House, is located on the opposite side of the Thames to Fishmonger Hall, where Usman Khan attacked a prisoner rehabilitation conference last Friday afternoon and killed two people.
Khan was shot dead by police after he was fought onto London Bridge and held at bay by a chef wielding a narwal tusk and a man with a fire extinguisher.
An hour later, Winckworth Sherwood sent staff a text instructing them to evacuate Minerva House as soon as possible. Half an hour later, it advised them to go home.
And then followed up with another, stating, "This is an emergency message from the WS DR System. In case you are concerned about month end, we will treat Monday as the last day of November for billing purposes."
Some staff felt the communication was misjudged rather than comforting.
"Considerate of WS to give an extra day for billing in the middle of a terrorist incident", said one. "No further comment needed", said another.
It may be the End Times -but it's also the last day of the month.
However, the firm appears to have calculated that some of its other lawyers are so worried about getting their hours up, they would ignore nearby screams, police sirens and gunshots.
“The messages were sent to ensure the safety of all members of the Firm", said a spokesman. "The highlighted message was meant to ensure nobody felt any need to return to the office or remain in the building”.