The auction of the typewriter will take place at Christies Auction House in South Kensington (85 Old Brompton Road) on November 30th 2005. The typewriter is to be in the "Modern Firsts" sale (a book sale).
Nic Davies who owns the typewriter says that the money will be used 'to raise money for Rhino Recovery''
Rhino Recovery's web site is at http://www.rhinorecovery.org.uk/ . The typewriter seems to be authentic and is signed by Douglas. And Nic quotes a mail from Geoffrey Perkins (H2G2 radio series producer) : "Douglas actually gave me the typewriter he wrote the show on many years ago but it is exactly the same make as the one you have! I would say in all honesty that you therefore probably have ONE of the typewriters that the show was written on !". More details and pics of the typewriter here.