At the risk of pointing out the obvious, use Google.

Tried that. All I can find is brief biographies saying “he was a great typographer”. I unfortunately need more than that for my assignment :(

Have you tried a good old fashioned library? I would bet that Mackmurdo is discussed in most books about Art Nouveau. There is a 1967 catalog of the Century Guild collection in print. Perhaps you can find a copy.

Here’s some information (all via google):

I know he has a mention in Meggs’ book.

Wikipedia: http://en.wikipedia.org/wiki/Arthur_Mackmurdo (not much, but a few book listed for reference.)
William Morris Gallery: http://www1.walthamforest.gov.uk/wmg/artsa.htm

His full name is Arthur Heygate Mackmurdo.

Mr. Arthur H. Mackmurdo and the Century Guild

Britannica entry on Mackmurdo

Evolutionary Affinity in Arthur Mackmurdo’s Botanical Design
Larry D. Lutchmansingh
Design Issues, Vol. 6, No. 2 (Spring, 1990), pp. 51-57 (article consists of 7 pages)
Published by: The MIT Press
(Available http://www.jstor.org/pss/1511437 if you have access to JSTOR)

A short listing, but has addresses to 2 of the homes he built:
http://eng.archinform.net/arch/7129.htm

Symbolist Art Theories: A Critical Anthology (Google Books) — Another research clue, look for more information on the “Century Guild”.

I didn’t know he did the Savoy hotel in London. I love that building.

http://www.all-art.org/history424.html — A strong statement that Mackmurdo “anticipated’ the style of Art Nouveau.

There are pages and pages. I did a search for “Charles Mackmurdo” (quotes included) and found all of this information. There’s a lot available. I’ll echo Kent in that you might have to do some book hunting in the library. The article listed above from MIT seems strong too. All of these links have tidbits. Google is your friend.

> Google is your friend.

Not to mention Google Books. Few of these are viewable online, but at least it’s a bibliography.