I have a problem, whereby I need to find the association between a legend
entry and a chart series (in order that I can do something with the legend
entry for a specific series if it exists).

I cannot find a way to establish a firm link between a series and its
legend, for instance:

The chart has 5 series.
The legend had 5 series but the user (or something/somebody) deleted 2 of
these legend entries so there are 3 legend entries.

So, at this point lets say I have code which has a specific series in its
hand:
Excel.Series series = _chart.Series(3);

And with this series I want to delete the legend entry:
Excel.LegendEntry entry = _chart.Legend.LegendEntries( <entryForSeries3 )

Is there something I am missing here? Or is there a method on an object that
I haven't seen that allows me to get the LegendEntry associated with a series?