I am contemplating changing my plates to "show plates" - however before anyone says these will be the correct font, spacing and"AU" reflective background.

The only thing which would not be legal is the plates would not have the "makers marking" and "AU" marking and on the road would look correct.

Does the MOT check these markings and therefore the car would fail the MOT? MY17 RRS 4.4d V8 Autobiography - Aintree Green (also referred to on Topix as British Racing Green)

I don't think most MOT testers would care, as long at the spacing was ok.

They do check them. They phoned me about my Mercedes saying they were illegal. Although I had a set of legal ones in the garage, I told them to get a set made up. Not worth the bother taking them up. To be on the safe side just swop them for a day for legal ones.

My car was MOT’d the day before I bought it and it failed for front number plate illegal.

Plate changed and it passed

I’ve got no makers mark on some of my plates and never had an issue but they meet the legal requirements in all other respects. I needed plates ASAP and didn’t have the opportunity to send a scan of my V5 so the online shop said ‘we can make them to legal spec, but can’t put our address on them as we haven’t seen your V5’. Another well intentioned law that doesn’t work. 2019 5.0 SC SVA (Current)
2012 5.0 SC AB. Sadly written off by a campervan
23 plate Focus ST (Current)
1942 VEP Ford GPW Jeep (Willys) (Current)
1943 Whites M16 Halftrack (Current)
16 plate Eurofighter Typhoon, 2 x Eurojet engines with 20,000lbs thrust each. 1380mph