Apparently the Abbey is occasionally closed on Mondays with no notice. The website indicates it was closed on 3/26/07, but I can personally attest it was unexpectedly closed on 3/14/07 and also on a Monday in mid-March 2006. Folks need to have an alternate idea of something else to do should they arrive for the walk and find the Abbey closed for the day. For a London Walks alternative, try the Inns of Court walk. It is an introduction to the English legal system, and led by Tom, a bona fide Barrister (who had much more personality and humor than any lawyer I have ever met).