I got my first response from Lauren, and sent my second back to her:
Thank you for your email, and please note my points in response below.
All M&S fitting rooms have lockable cubicles designed to protect each customer’s privacy.
Many of which have gaps under and over the walls, which can be used to peer over or observe or record with a phone.
As a business, we strive to be inclusive and therefore, we allow customers the choice of which fitting room they feel comfortable to use, in respect of how they identify themselves.
However, if your customer has been of the female sex (ie since birth) you don't have a choice available which meets the needs of those of us who want to share only with others of the female sex (from birth). Therefore there is nowhere for us to change in your stores where we could feel comfortable as there may be male born people there.
This is an approach other retailers and leisure facilities have also adopted.
Irrelevant
We understand your concerns
I dont think you do.
and I want to make it clear that if any customer was to act inappropriately or cause intentional offence, the necessary action would be taken.
Too late when someone's scarpered after filming you undressed, or worse. How dare you put women and girls at risk like this!
Please address my latest points.