Vista - Finding a RotateTransform somewhere in the visual tree

I need to find out the rotate transform applied from a low level part of the
tree, e.g.

Lets say I have the following:

<StackPanel x:Name="commonpanel">
<StackPanel x:Name="foo1">
<StackPanel.RenderTransform>
<TransformGroup>
<ScaleTransform ScaleX="1" ScaleY="1"/>
<SkewTransform AngleX="0" AngleY="0"/>
<RotateTransform Angle="90"/>
<TranslateTransform X="0" Y="0"/>
</TransformGroup>
</StackPanel.RenderTransform>
<TextBlock x:Name="textFoo1">Foo1</TextBlock>
</StackPanel>
<StackPanel x:Name="foo2">
<StackPanel.RenderTransform>
<TransformGroup>
<ScaleTransform ScaleX="1" ScaleY="1"/>
<SkewTransform AngleX="0" AngleY="0"/>
<RotateTransform Angle="180"/>
<TranslateTransform X="0" Y="0"/>
</TransformGroup>
</StackPanel.RenderTransform>
<TextBlock x:Name="textFoo2">Foo2</TextBlock>
</StackPanel>
</StackPanel>

In my case I need to find the current angle of the 'textFoo1' & 'textFoo2'
visual elements, in relation to the 'commonpanel' visual element.

textFoo1.TransformToAncestor(commonpanel) does not seem to help as it
returns a GeneralTransform.. The code that needs to do this is generic, I.e.
The StackPanel/Angle etc might not exist at all.

Any ideas ?

Regards

Andrew