In reply to jon:
> MFS 732 C32 (which I take to be 32A). It is clearly labelled 'cuisinière'
Cool. That's the correct item.
> The socket and plug which you linked are indeed what our electrician installed in our other house.
The regs now say one must be installed in every new house or complete rewire.
The 'adapteur' is a consumer item, as is your cooker.
You can choose to plug it in or not. It is not covered by the normes for electrical installation in your domestic property.
You can plug whatever you want into a socket. Its a free world.
What you can't do is wire up the house incorrectly.
The fact is, if your existing 16A cooker with its 16A plug and 16A cable shorts then it is going to take considerably more than 32A and will trip the disjoncteur very quickly. It is safe.
After all, you plug your 5A table lamp into a 16A socket every day?
If however you fit a 16A socket to the 32A circuit in the location that is obviously for a cooker then someone may be tempted to wire up a 7kW double oven using a matching 16A plug.
A 6kW oven will draw a max of around 25A.
Your disjoncteur will not trip, your thick wires (prob 6mm sq) will be safe and will not overheat. Your 7kW oven will be fine as it and it's wires are rated for this.
Your 16A socket and plug will be running at over 150% of their rated amperage. They will probably set on fire.
(Amongst other design considerations, a 16A socket will not have suitable clamps for the size of cable that is in your wall. Even if you get them to fit you will not have a high contact surface area. The current is forced though a tiny metal-metal contact area heating it up.)