Large, free standing electric cookers (Ranges) do need to be on a separate 32A radial circuit.
Annemarie1s' mums 'oven' could be just a single built-in oven (no cook top). These often have a rating of around 2.4kW @ 230V and come fitted with a 13A plug. They are intended to be plugged into the general kitchen ring final just like anything else.
Alternatively, it could be a 'full size' cooker connected to a dedicated 32A radial using a 'cooker control unit'. These often incorporate a 13A aux socket (in days of old, that could well have been the only 13A socket in the kitchen) so the plug strip could be plugged into that...
A third alternative is that the house has only the one RCD and that is the main switch. Not really upto code anymore but thousands of installs like that (including mine).
