Absolutely! Wikipedia is maintained by volunteers who find references to stuff but don't necessarily do the research themselves. I saw a debate once between 2 Wikipedia writers about my research into Hulme Athenaeum. One suggested putting a new page up on the team (Lancashire's earliest known team) because of my research. The other said something like 'no way, just because some bloke's written it doesn't mean it's true' - a line id agree with but if they actually did the research and gone through each and every reference I'd researched myself they'd have known it was true. Basically, if 1 person decides to write something on wiki it gets accepted until someone else changes it. People can do this for all sorts of reasons. Bottom line is that Wikipedia can be useful as a starting point, but it is not necessarily factual, accurate, balanced or thorough.
St Mark's history is well documented in my Manchesyer The City Years and the opening chapters can be read for free in the Look Inside feature on Amazon. Well worth doing. Cheers. It's not even a Maltese Cross by the way. It's a cross Patee