Sounds like they did release them
[link|http://www.bnn-online.co.uk/comments_display.asp?HeadlineID=3608&Year=2006|British Nursing News]
Cabin crew who came into contact with the woman have been told to monitor their health over the next week.
To me that implies they're on their own. Also, no one else seems to have picked up on this. I can only find verbatim copies of the Mirror article through Google, and the Belgian on-line papers didn't carry this at all. If 270 people were forced into quarantine at Heathrow, I'm certain that would have been a headline all over the map.
And this was three days ago. A targeted diagnostic test can give an answer in less than a day (see "Diagnostic Tests" @ [link|http://pathport.vbi.vt.edu/pathinfo/pathogens/Ebola_2.html|http://pathport.vbi....gens/Ebola_2.html]), so this shows signs of a non-event.