Sorry, their whole site has been rejigged. I don't think the relevant minutes are there now, but I managed to find them in a Google cache -

http://64.233.183.104/search?q=cache:zKMoWbqXLF8J:www.english-heritage.org.uk/FileStore/about-us/pdf/ehac/EHAC_minutes_Feb05.pdf+%22english+heritage+advisory+committee%22+2005+Silbury&hl=en&ie=UTF-8