Fowler's Modern English Usage says re the hence, whence, thence, henceforth etc word-group..."The most stubborn survivor of this set of phrases is from whence, a phrase with a long and distinguished history."
And that it certainly has. Shakespeare was happy to use it, as were Dryden, Goldsmith, Dickens, Swinburne et al.
Yes, the from is generally redundant and the phrase as a whole rather old-fashioned, but what the hey! I can't think of any good reason to dismiss it. If Coleridge can write...
"Alone, alone, all all alone,
Alone on a wide, wide sea"...
I'm sure Sir George was perfectly free to say from whence!