Thanks and a good idea/option if the above don't work.Can you thread a cord round the lower yoke of the lock?
If so, diamond paste pressed into the cord and saw it off like those two handed flexible tree saws they sell for camping or on a larger scale like they sawed the Kursk in half with a hawser that had abrasive collars threaded on.
(Yes industrial diamond paste is available - no need to crush the wife's engagement ring!)