They were banned 5 years ago?
I left the blue hellhole five years ago, and I'm pretty sure they were banned already then... despite the fact IBM branded USBs were available to order from the branded marketing catalogue.
Also recall the CD/DVD drive on the Thinkslab was locked out. Extremely clumsy BitLocker (or similar) drive encryption which required unlocking even coming off screensaver.
I've also got a vague memory of the corporate BlackBerry having some shit-awful MDM smeared over the top, because BES wasn't enough.
The paranoia extended to travel policy - if you needed to work on a train journey, you HAD to travel first class... which given I had to lug the laptop about with me everywhere, meant I always travelled in the slightly less shit seats on Southern.