I managed to get one reply to this advising to try the Pinch/Punch effect in Sony Vegas, which I have experimented with but unfortunately it does not seem possible to configure the settings to reverse the barrelling distortion.
While the footage is frozen on one frame and the picture is 'squeezed in' to the centre, yes it looks almost fixed... but once the footage is played and the camera is moving, it is clear that this post production application cannot simply flatten the image by reversing the magnification effect created by the wide angle lens.
You would think that considering the wide angle lens is round, with its magnification properties symmetrical and peaking in the centre, that one could apply a reverse magnification in exactly the same place of the footage as a counter balance.
I also cannot believe after searching the internet that this problem is not more of a concern - 'don't buy cheap lenses' seeming to be the most popular comment here, but while we all should know we get what we pay for, there must be an application or plug in for some editor somewhere than is programmed with the maths to fix this ugly, and very common, 'barrelling'?