Isn't this due to the huge problems pretty much every prison is having in recruiting and retaining staff?
I recently heard some interviews on the radio, and realised that the prison service is so desperate that:
(a) there is much less vetting than there was in the past - and some recruitment is being done online, rather than with a face-to-face interview
(b) the length of time spent training new officers (teaching them how to deal with highly manipulative prisoners etc) keeps being cut, shorter and shorter.
In Norway, aspiring prison officers are expected to undergo a university-accredited course lasting two years. The situation varies widely around the world - in most places there is a mixture of formal and informal training, shadowing etc - covering all the knowledge and skills required - but in the UK the basic training now only lasts something like 10-12 weeks!