Finding starting point of chart plot area

I want to add some vertical lines to an Excel chart, so I started off by finding the dimensions of the chart and plot area, using the following:

    ActiveChart.ChartArea.Select
    L = ActiveSheet.Shapes(MyChart).Left
    T = ActiveSheet.Shapes(MyChart).Top
    W = ActiveSheet.Shapes(MyChart).Width
    H = ActiveSheet.Shapes(MyChart).Height
    ActiveChart.PlotArea.Select
    PL = ActiveChart.PlotArea.Left
    PT = ActiveChart.PlotArea.Top
    PW = ActiveChart.PlotArea.Width
    PH = ActiveChart.PlotArea.Height

My problem is with the PlotArea.Left -- If I relocate the plot area to the far left, I get a value of 0, which is the left edge of the Y-axis scale. The actual plot area is further to the right.

How do I find the left edge of the actual plot area?