A minor housekeeping point, you might also consider adding the author's name for "The history and topographical survey of the county of Kent..." so that it is formatted consistently with your other sources. Example:
Hasted, Edward. The History and Topographical Survey of the County of Kent. Vol 3. (1797), pp.275-300
would better mirror your existing reference:
Maidment, Barbara. A History of Groombridge Place, 2nd edition (2005), p.24.
--- expanded discussion ---
I realize the version you have used of the Hasted reference is the default citation generated by BHO, but if you use their tool to generate the citation in other formats, you will find every other format includes the author somwhere in the citation. Using their MLA citation as an example:
Edward Hasted. "Parishes: Speldhurst." The History and Topographical Survey of the County of Kent: Volume 3 (1797): 275-300. British History Online. Web. 04 September 2013. <http://www.british-history.ac.uk/report.aspx?compid=62858>
--- sidebar/digression ---
I would however argue that BHO's MLA format is incorrect/outdated. In MLA: author is given surname, given names/initials; the publisher information should still be given if known (in this case it is) and the overall reference should arguably read as:
Hasted, Edward. "Parishes: Speldhurst." The History and Topographical Survey of the County of Kent. Vol. 3. Canterbury: W. Bristow, 1797. pp.275-300. British History Online. Web. 04 September 2013.
As we (wikitreers) like to include links to references where possible, it would be appropriate (in keeping with MLA format) to include the link in it's usual spot at the very end of the citation enclosed in angle brackets, or to just link the chapter or work.
