Tonight’s seminar is on Gustave Doré, and 1872’s London: a Pilgrimage in particular.
Quite a lot of Fantasy and faith: the art of Gustave Doré (ed. Eric Zafran, Robert Rosenblum and Lisa Small; Yale University Press, 2007) is available on Google Books. Only a few pages of this study (these) are devoted to the London book, although they are pretty interesting. But the whole volume has illuminating things to say.
This 1866 Contemporary Review comparison of Millais and Doré is interesting, too; although obviously it predates the London book.