I am with China on this one.  I am sure some ladies followed QV's lead closely, as many will follow a celeb today.  But do not believe everything you read on the web - I suppose even this site, but we know we are only expressing opinions, some more knowledgeable than others.  Anyone can publish anything on a website.  Just Google "Victorian dress" to get a range of lovely colours!
Of course it could also be someone mourning QV herself, the date is about right.
Kath