Pros
Great responsiblities from your first day can lead to rapid skill and experience accumulation in a short time. Culture can feel almost like a family, strong emphasis on food and spending time outside of work together, which can make it easier for those working in the London for the first time, who may not have friends outside work. Good opportunity to learn spanish as well as other languages from site.
Cons
Risk of burnout, little recognision for effort, long hours, little support, work life balance was not great. Pay desparity, some engineers received increased pay on attainment of professional qualifications, charterships etc, I did not for the same qualifications. Promised pay increases for specific groups with same experience level, differed. We were promised set salary figure after completing graduate program. On receipt of letter with new t&cs, my figure was lower that had been quoted. I later found out the other engineers had received their promise pay increase as promised.