It actually failed last year on its MOT (A few months before I purchased it) but it failed on the front suspension arm, pin or bush which were then replaced for a pass. No mention of any corrosion though.
It’s been over 16 months though since the last MOT was done due to the covid-19 6 month extension on it.
Looks like going who dares wins and hoping for the best. You’ve answered the main question for me though, that a taped over hole at the bottom of the outer wing is not necessarily an automatic failure on these.
Cheers