It's the DM, I've seen a thread or two on GWR blocking Sex Matters. I think it was originally reported in the Telegraph. The DM seems to have taken that ball and run with it.
https://www.dailymail.co.uk/news/article-12400923/Sinister-disturbing-emerged-gender-critical-websites-blocked-train-wifi-probe-shows-scandal-stretches-far-wider.html
GWR said it was because of the word 'sex' but that seems to have been nonsense. It's now been unblocked.
Has anyone had problems accessing GC websites when out and about? Sex Matters, Transgender Trend.....Mumsnet?