No hyper refs from citation to bibliography using BiBTeX, hyperref and harvard

The hyperref package is known for not being entirely compatible with many citation manager packages, with the main exception of natbib. (I.e., hyperref is fully compatible with natbib.) While it's true that the user guide to the hyperref package notes that the harvard package is "supported", the next sentence in the same paragraph of the user guide states that "the recommended package is Patrick Daly's natbib package".

Fortunately, you need not change your harvard-style citation commands to equivalent natbib-style commands in order to get full interoperability with the hyperref package: there is a nifty little package called har2nat that performs these translations for you. Thus, if you replace the instructions

\usepackage[abbr]{harvard}
\citationstyle{dcu}

in your MWE with

\usepackage{har2nat}   % loads "natbib" automatically
\setcitestyle{aysep={,}} % needed to fully emulate harvard's "dcu" citation style
\citationstyle{dcu}  % provided by the "harvard" package

the hyperlinks from the citation call-outs to the corresponding entries in the bibliography are formed correctly. Observe that you should not load the harvard package with this setup.