Is this where the word 'spam' comes from?

When did we start referring to unsolicited marketing messages as ‘spam’? While researching my book, I found an article ‘The regulation of unsolicited commercial communications (spam): Is the opt-out mechanism effective?’ by Sebo Tladi in the 2008 South African Law Journal. The article discusses, amongst other things, the history of the word ‘spam’ and speculates that it comes from ‘a Monty Python skit in which a group of Vikings sang a chorus of ‘Spam spam SPAM’, with increasing volume in an attempt to drown out the conversation.’ To understand it at all you have to know that ‘spam’ also refers to canned meat; not unlike what South Africans will know as bully or corned beef, I suppose.
In any event, here is the Monty Python skit.