Tale of the missing libphp5.so
A recent Debian package update appeared to remove PHP from Apache's configured modules. As a result when apache restarted I was presented with:
Cannot load /usr/lib/apache/libphp5.so
A quick search using locate was my first port-of-call resulting in ziltch.
So a rather simple command plus restart solved the issue:
apt-get install libapache2-mod-php5 apache2ctl restart