G-ASYD was the prototype and served 29 years as demonstrator and test aircraft in various configurations. It was used even for flights controlled remotely. After its faithful service its preserved at the Brooklands Museum.:
We can fly her in FS 2004 in the perfect simulation of David Maltby:
It is in the configuration BAC 1-11 475 HK means it has the shorter airframe, the power of the 500 version and sturdier legs to land on unpaved runways and it was hush-kitted to allow its use under stricter noise regulations.
I guess the content is still on the Simviation server but no access as the domain ran out, hopefully Dave Maltby will look at that?
As we are also hosted by simviation simviation.com/hjg/ Im sure Dave if he is still about can drop the domain name and go with the simviation.com listing as we have done, but if he is not active then I guess the files will stay locked away
In the meantime, until David's site hopefully comes back, you can "go back in time" and access it on the Wayback Machine (here), including the files, not just the bare website.
Some of the files seem to be archived, which means they can be downloaded straight off the archived site. Others are not. For those files which haven't been archived, you can simply copy-paste the download URL of a particular file, remove that part of the URL pertaining to the Wayback Machine and just leave the original URL (without the Wayback Machine part), hit enter, and the file should commence downloading straight from the Simviation servers.