Sex work?
stupidpol
Socialism for sane people
on p.3 of the pdf is a link to a spread sheet which gives a breakdown of the kind of offenses. here's the screenshot

Most of them were for rape.
What the hell is going on in the UK? These numbers make no sense.
The linked PDF shows 163 trans women is 59%. So, 163/6~27, so there are about 270 trans women incarcerated in the UK. There are about-90k prisoners in the UK. I believe that sample size is too small for any real information.
These are probably better examined on a case-by-case basis, especially with a low sample size like that.
I definitely would look deeper into the data to draw any conclusions. It is the BBC's sacred duty to endanger as many transgender people as possible, and so I have every expectation that it's biased against the trans community.