Well, the Saab went in for it's MOT today and failed because an Exhaust Particulate Filter is missing but is fitted as standard and should have been there. It was gone and there was just a pipe welded on where it should have been.
We drove across to the independent Saab dealer that sold it to us, with full MOT that they did, the owner not there but his son was (a right sheister, IMO) and he said that last year, when it was tested, the regs said that there didn't need to be one fitted, so that fact it's been removed (not by the Saluki household) was OK, but they changed the regs on 1/1/16 and now we've fallen foul of it.
Having spoken to our MOT guy, who says that this is BS of the highest order, which is what we thought, I thought I would just ask the question from someone we are not friends (in real life) with but who might know when the regs were changed, as we are pretty sure it wasn't last week.
Our nice MOT chap had no internet up at his place, otherwise, he'd have looked it up.