I have the VHS and now they have it on DVD. I would highly recommend this. John Britten was a GREAT engineer, too bad his life was cut short.
http://www.brittendvd.co.nz/index.html
Here's a great documentary of Britten in '93.
http://www.nzonscreen.com/title/britten-backyard-visionary-1993
(http://tpo.tepapa.govt.nz/Images/PictureWM/TPOPRO001800_WM.jpg)