Did you know that these days there are three spark plug sizes? - for decades there were two, and you can guess where this message is heading.
Apparently manufacturers are making smaller engines, although I see a ridiculous number of fat cars driven and parked with little skill. One step was to shrink the plugs, the smallest has an M12 thread needing a 14mm AF socket/spanner.
The other good news is the Renault engine has precisely a 20mm vertical tube 6in long (through the rocker case) with the plug at the bottom. Both the new Bosch FRD7C plugs and conventional spark plug sockets will not fit within 20mm.
Here are a 14mm AF plug (from the engine) and a 16mm AF plug that I bought:

I can recommend the Laser 14mm thin wall socket, 250mm long with an outside diameter of 18.2mm and knurled end for quick finger spinning of the long thread. It has a magnet to reliably lift the plug out of the long tube. I bought it from Amazon
https://www.amazon.co.uk/dp/B00372FILOSo if anyone needs some 16mm FRD7C plugs they are up for grabs.
-Paul