Dolly Varden was a character in Barnaby Rudge, a popular Dickens novel, published in 1841 in weekly installments that was set during the anti-Catholic riots in London of 1780. This and more information can be found at David Perdue's Charles Dickens Page, which also has a link to the entire novel online.
The Christmas card has no date. The inside greeting looks more like a rubber stamp than a fine printing.
Here's a tidbit about the Dolly Varden character from David Perdue:
Victorian readers were quite taken by the spoiled, coquettish daughter of the honest locksmith, Gabriel Varden. According to Vanda Foster and Richard Dunn in the Dickensian, Dolly inspired songs, dances, paintings, 'the Dolly Varden look' in ladies' fashion in the 1870's, and lending her name to a hat style, a spotted calico material, a species of trout, a variety of horse and the buffer on a railway tender.
William P. Frith's famous painting of Dolly Varden, now in the Victoria and Albert Museum, was taken from the description given in chapter 19 of Barnaby Rudge:
"As to Dolly, there she was again, the very pink and pattern of good looks, in a smart little cherry-coloured mantle, with a hood of the same drawn over her head, and upon the top of that hood, a little straw hat trimmed with cherry-coloured ribbons, and worn the merest trifle on one side-just enough in short to make it the wickedest and most provoking head-dress that ever malicious milliner devised."Here's the Frith painting of Dolly Varden posted on Perdue's website:
Goodness, just when I think I'm done, I come across some more information that I can't bear to leave out. Here's a blog that describes the Dolly Varden fashion craze: ZipZip's Vintage Sewing. I do recall seeing a Dolly Varden paper doll in an auction catalog somewhere...