Why are transmen not trying to get into Mens prisons?
Custodial institutions which cater for women in the estate are statistically much safer than establishments than men. They are considered, on the whole, more comfortable residences. There are also fewer female to male people in custodial settings too.
In England and Wales, you cannot transfer between the male and female estates without a Gender Recognition Certificate. No person in a custodial setting has ever been granted a GRC whilst in custody. If you enter custody with a GRC, under prison policy, you will be assigned to the custodial institution you are legally recognised as. If you are a female to male transitioned person, you can request to reside in the female estate.
Statistically speaking, people who are assigned a male gender at birth are overrepresented in the custodial population than those born as female. In June 2023, 96.1% or people in custody were legally men, 3.9% women. In our general population, according to the 2021 census, 51% of the population, in the UK, were born as female, 49% were born as male.
You are far more likely to be born as male and be in a custodial setting than female. Considering that the trans* population, or breakdown, of either gender is incredibly small, this can explain why there is a higher proportion of MTF people in custodial settings than FTM.
Conversely, the breakdown of legally recognised transitioned people with GRCs in England & Wales' custodial estate, is about 50/50. The overall number of transitioning prisoners, or those who identify as transitioning, without GRCs is higher within the male custodial population, but this could be explained by the size of the male custodial estate alone.
Male to female residents, in custodial settings, are not trying to move to the female estate. The MoJ has received very few transfer requests over the decades, the exact numbers haven't been released but they are of a trace amount; this is explained by the inability to transfer estates without a GRC.
Why would "non-genuine" people in a male custodial setting wish to identify as another gender? Most of this comes to comfort and misconceptions within the custodial population. If, in a male establishment, you identify as female you are granted a single cell. You are treated as female, within the establishment, but crucially cannot transfer out. You are granted your own dedicated shower time, if you don't have an in cell shower. It used to be the case that if you were a transitioning person convicted of a sex offence you wouldn't be able to complete a behaviour rehabilitation course, or "programmes", this is no longer the case but there are those still believe it to be true.
Essentially, you get an "easier" time, or more (what could be seen as) perks, if you identify as female in a male custodial establishment. You are never encouraged for any further commitment, you do not need to prove anything, you do not need to carry on living your trans* life after the perceived benefit stops. It should be noted, however, that this is obviously not the norm in the rest of society, nor is it the rule of trans* experiences in prisons. This just explains why some people attempt to transition, or declare as transitioning, whilst inside.
It is nothing to do with a person born as male attempting to transfer into a female establishment, in order to commit acts of sexual assault or for sexual gratification. It's a dangerous trope and an awful misconception.