You can buy a copy from EFDSS (you already know the address) or perhaps borrow it through a library, though only the more specialised ones subscribe. The piece is a good general overview (33 pages, I think) with some interesting musical examples as well. I think the Vaughan Williams Memorial Library will photocopy articles for you, but it probably isn't a lot more expensive to buy a copy of the Journal; they still have a fair stock of the more recent numbers.