An Empire of Stars: Forgotten history of the the British Space Programme

This article implies that the codes for communicating with Prospero may still be available:

       http://www.dailymail.co.uk/sciencetech/article-2034379/Quest-revive-space-relic-lost-1996--British-launched-satellite.html

Also, this blog post from 2012 says they haven't given up:

           https://web.archive.org/web/20121026003633/http://blogs.ucl.ac.uk/prospero-satellite/2012/04/04/long-overdue-update/

I can't find anything more recent -- but doesn't seem entirely hopeless.

One of the major reasons for the cancellation of the space program was Britain was at the same time developing Concorde (with the French). There was only enough money for one of them and it was decided concorde was more likely to be commercially successful.

Other people think concorde is an masterpice of engineering but I'd have preferred the rockets.

On the other hand a lot of the research and technology went into the European Space Agency so it wasn't a total waste.

There's a whole chapter on the last gasps of the British Space Program in the book, Backrook Boys

http://www.goodreads.com/book/show/1331484.Backroom_Boys

If you're interested in this topic, you may enjoy the alt-hist comic book "Ministry of Space", set in a world where the UK space programme is much more successful.