I checked and the page is no longer active.
I had access to it sept 3, 2015 and then it has been a
very detailed 18-page document.
The e-mail of the author given in this document
has been:
wolverhampton-glms (at) fsmail.net
or
cvcl (at) wolverhampton-gunlocks.fslife.co.uk.
Author has been C.V.Clark with last revision of document
april 2015.
Propose to contact him by e-mail, if this
does not work, then I recommend you to contact
the Holts folks, they should know where to continue.
Cheers
Felix
Any eMail/web addresses with "fslife", "fsnet", "fsmail", "freeserve" are likely to be out of use because the organisation that supplied them (FreeServe, an early UK based ISP) was taken over by Orange and those addresses were closed.
