How can I obtain an instruction manual for a Vulcan Continental gas boiler?

All I know is that it is a Vulcan Continental. There are no panels or labels on it. It is in perfect working order and I wish to keep it for the time being, I need some technical information to enable me to relay this to an engineer so that he is able to issue a certificate for it. I was informed that a set of full instructions were downloadable on the web!