There is a new book encapsulating Dr Alabaster's work on Elizabeth Poston's papers.
Elizabeth Poston: Catalogue of Works with Biographical Context
It is available via via http://www.lulu.com/shop/john-alabaster/elizabeth-poston-catalogue-of-works-with-biographical-context/paperback/product-23663053.html#expand_text  

Before that there were five books and a DVD to tie in with Elizabeth Poston and the 2005 celebration. Those five are out of print and unavailable through us.

There has also been an article in Hertfordshire Life magazine, see 
http://www.hertfordshirelife.co.uk/people/the_remarkable_miss_poston_1_3703985

DVD:

Elizabeth Poston at Rooks Nest   ISBN 0-9550669-1-3

Books:

Elizabeth Poston: Letters to William and Sheila Busch by John S. Alabaster (Editor) and Julia Busch.  The Foreword is by our Chairman, Mervyn Terrett.  Her letters make clear how much she relished the tranquillity of this part of Hertfordshire.   The correspondence also gives many fascinating insights into 1940s musical life.

Elizabeth Poston: Her Own Words. This focuses on her attachment to the house and surrounding Green Belt Forster Country, drawing on the very large number of letters she wrote to her close friends, particularly to Canadian composer, Jean Coulthard from the 1940s, as well as her incomplete autobiographical drafts. It also includes correspondence from the 1930s relevant to Peter Warlock.

Elizabeth Poston, composer - Her life at Rooks Nest by Margaret Ashby
ISBN 0-9550669-0-5

Elizabeth Poston Centenary, 2005 Contributed Articles and Personal Letters
edited by John Alabaster
ISBN 0-9550669-2-1

 Elizabeth Poston Post-Centenary 2005 Appreciation More Letters, Tributes and Articles
edited by John Alabaster ISBN 0-9550669-3-1

Elizabeth Poston Centenary, 2005 Contributed Articles and Personal Letters
edited by John AlabasteISBN 0-9550669-2-1

 Elizabeth Poston Post-Centenary 2005 Appreciation More Letters, Tributes and Articles
edited by John Alabaster ISBN 0-9550669-3-1