Had an mot on my Corsa last week.
It was passed but had an advisory about a split windscreen wiper which was replaced by us the next day.
Comes under the visibility section with mirrors.
So you may pass but have to do it ASAP...or before may be wise.
As I understand it, not on the nearside, providing you have two other mirrors. BUT, an M.O.T tester can deem it as dangerous if they care to and fail it.
According to this link the nearside wing mirror is an obligatory mirror and a slight crack is a minor fault, a missing or badly damaged mirror is a major fault
https://www.motester.co.uk/mot-test-of-mirrors/
Thanks everyone. Without checking with an MOT station it looks like a N/S mirror with the lens missing IS an MOT failure. I think it's fairly new legislation.
Cars first used before 26th Jan 2010 require 1 O/S mirror and 1 of either N/S or Internal mirror provided it gives the driver an adequate view to the rear.
Cars first used after that date require 1 O/S , 1 N/S and 1 Internal mirror (unless the internal mirror cannot provide an adequate view to the rear).