I'm assuming that either you are certified as a competent person to be carrying out electrics in special locations such as bathrooms and kitchens, and adding new circuits, or that you notified this work to your town building control officer and have had it tested and signed off? Otherwise what you did is illegal whether your work is technically correct or not, though you won't be the first, nor the last. I think the question is more an electrical one than a plumbing one however, so this forum may not be the best place for an answer.Your post made me panic until i realised that my boiler is in the bathroom but it is fitted in the airing cupboard complete with a door so in effect a separate room. Im assuming your quote relates to mounting switches on the wall in the actual bathroom, not a cupboard within it?
With regard to your airing cupboard technicality and putting aside regulations for the moment (I'm sure others will be happy to lecture you on the potential dangers of DIY electrics but I can't be bothered myself), I would be inclined to consider whether the switch is likely to come into contact with a naked person who is covered in water, or not. Surely that is why in the UK we can't have switches in bathrooms (within 4m of a bath or shower IIRC) (though they do abroad and they seem to survive)?