Ive seen it a few times in park homes, or holiday homes (static caravans to you and I)
The space in the shower room, if theres enough room to fit in a washing machine or tumble drier or something.... so Danny DIY goes and fits a double socket.
Had to remove anything like that if we were tasked with selling the caravan on.
Some homes came new with the boiler cupboard inside the bathroom.... behind a cabinet door, turned out to be about 1m from outside the shower cubicle door...
All these newer units had an RCD mainswitch in their own CU, plus the 16A RCBO hookup from the park. (2 x 30mA in line.... never good)
I doubt if theres a difference in the electrical regs between a holiday unit, and whats classed as a residential unit... differences in the build. (higher ceiling, more floorspace in bedrooms) but should be no difference in wiring regs.
But back to the OP... Im certain no future editions will allow it. No one knows how long flexes could be? so you could have the situation of a radio, or small plug in heater sitting precariously close to a bathtub full of water and wet human.
If someone wants to do it with extension leads from the landing, then that's where Darwin Awards get their nominations from.