Alfred Lord Tennyson had quite long hair, although not a Hartnell-ey cut. I thought Disraeli had long hair, but it looks like he only had it as a young man, and in ringlets, so not really the same thing.

US President Polk had a somewhat Hartnell-ey similar haircut, although that's 1840s, not late nineteenth century.

I feel there's a really good example that's just escaping my memory...