Yes, probably, for the reason you give (and possible others) - but, if it's 'plugged in' I'm not sure which regs (I'm sure others will know!) - BS7671 only relates to 'fixed wiring'.Dont know if im being silly but is it against any regs of some sort for using a pattress box as an extension lead? dont they need cord grips?
It's certainly not good practice if the socket/box are 'lose' and the cable not secured or clamped in any way. However, nor is it uncommon
Kind Regards, John