UBS UK had the worst working culture I've ever seen. My workload was always 5 times more than what I realistically could achieve, so I always ended up delivering around 200%. This led to my complete burnout and snap resignation.
Long hours were expected, and if I made even a small mistake, I'd have 3 managers pull me aside.
The place was also extremely political. To be in good graces on the Senior Trader was everything, as one word from him could make or break someone's career. This meant that an incompetent ED with no IT management skills was promoted to manage a large IT team only because of that relationship. His incompetence led to 15 people leaving the team within 18 months.
I don't recommend working at UBS. Don't be swayed by the prestige and high salary. The cost of this is your mental health.