This has been raised not long ago, if the cupboard that the washing machine is in can be locked or needs some other tool for access then you can have a socket, but as to when it forms another room does not seem to be so clear, we have a definition for habitable room, and occupiable room, but not simply a room.
We have sizes with 2.25 meters high being limit to bathroom regulations, but the 3 meter rule for a socket in a bathroom is not the same as the 0.6 meters that defines zone 2 after zone 1 ends.
But first catch the monkey. So if there is no requirement for some one to do an EICR, and no one gets injured who will know if the rules are broken? Where the problem lies is when rented property and some one needs to complete an EICR, even then it is potential danger not non compliance with regulations.
The 3 meter rule in a bathroom replaced the 3 meter rule in a bedroom for a shower, basic idea is if there is a shower in the bedroom a socket needs to be over 3 meters from the shower.
However it is the definition of a room, last house I had a dinning room and living room separated by an arch, no door, so clearly a door is not required to make it into a room, and the regulations don't refer to a room they refer to a location.
So it seems doors count but curtains don't! so is this
View attachment 219603 a shower room, and outside the glass partition is not part of the bathroom assuming no bath? Since that would be likely what would be installed in a bedroom, that would mean no need for 3 meter rule in a bedroom, the shower is considered as being a separate room off the bedroom. But some how can't see the LABC agreeing with that, so if that shower cubical is not considered a room, neither is a cupboard in a bathroom with a washing machine in it considered as a separate room.
As said if safe, i.e. unlikely to get wet, and RCD protected then for owner occupied who cares, just do it, but if some one needs to inspect and write a report, not so sure, I was told off by LABC for not notifying them that a toilet and pantry had been turned into a wet room, seems it need notifying so would assume same in reverse, if you turn a space that was a bathroom into a room for some other use, they need notifying. In real terms I would only do it when they are going to find out anyway, however if I was renting a house with a washing machine in the bathroom I would not fit a plug and socket anywhere that could be considered a bathroom, unless no other option, and then even if never actually locked, I would put a lock on cupboard door.
I will be interested to see what others say, the main point is if they found it when doing an EICR would it get a code C2?