Currently in the UK, there are 82,159 men in prison and 3,948 women.
So if we see that a male is 20x (approximately) more likely to be incarcerated than a female, we now need to ask ourselves how many trans prisoners are likely toin the presence of a "trans-friendly" policy that allows MTFs into women's prisonsenter these prisons.
It's hard to know the prevalence of transgender identity but most organizations say it's around .5%, or one in 200. So if 1/200 males in the prison system decide to voice that their gender identity is "woman," we can expect to see 410 MTFs enter women's prisons, which will mean that more than one in every ten prisoners in every UK women's prison will have been born with a penis.
Sex offenses are seven times more likely to be committed by males than femalessee www.gov.uk/government/uploads/system/uploads/attachment_data/file/220081/statistics-women-cjs-2011-v2.pdf--14% to women's 2%which means 57 of those male prisoners would be likely to be sex offenders, while only approximately 80 women prisoners total have been convicted of sex offenses. So between 1/3 and 1/2 of sex offenders in British women's prisons would have been born with penises. Since the criminality patterns of MTF people match up MUCH more closely with males than females [http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0016885%20], these statistics are likely to become reality with a trans-friendly policy.
Is that acceptable? Because these are the numbers we're talking about. Given the prevalence rates we've been told by advocates for trans people, this could get very difficult, very quickly. This is especially true in light of the testimony recently given to Parliament by the British Association of Gender Identity Specialists (hardly an anti-trans organization):
"The converse is the ever-increasing tide of referrals of patients in prison serving long or indeterminate sentences for serious sexual offences. These vastly outnumber the number of prisoners incarcerated for more ordinary, non-sexual, offences. It has been rather naïvely suggested that nobody would seek to pretend transsexual status in prison if this were not actually the case. There are, to those of us who actually interview the prisoners, in fact very many reasons why people might pretend this. These vary from the opportunity to have trips out of prison through to a desire for a transfer to the female estate (to the same prison as a co-defendant) through to the idea that a parole board will perceive somebody who is female as being less dangerous through to a [false] belief that hormone treatment will actually render one less dangerous through to wanting a special or protected status within the prison system and even (in one very well evidenced case that a highly concerned Prison Governor brought particularly to my attention) a plethora of prison intelligence information suggesting that the driving force was a desire to make subsequent sexual offending very much easier, females being generally perceived as low risk in this regard. I am sure that the Governor concerned would be happy to talk about this."
data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/women-and-equalities-committee/transgender-equality/written/19532.pdf