In the thread on Vaughan Williams day at Cecil Sharp House there has been some discussion about how membership of the EFDSS would work if you were to join now. This is the definitive answer from the membership secretary...
It's more obvious if you think of all memberships ending on 31st December.
People who join in the autumn, paying the full 2008 rate, get membership for the rest of 2008 and all of 2009. A bargain!
English Folk Dance and Song Society
The Yorkshire Polymoth