Serco Group Project Manager interview questions

Applied for this role in January, got a response in April for interview 4 months later. Got to the interview and my name was missing from the list. Long story short - I was offered some figure plus company car but I tried to negotiate.. The offer was immediately rescinded and given to the next candidate. To be honest I was shocked - I thought salaries were meant to be negotiated. Felt it was abit arrogant of them. Well didn't bother much because I had another well paying one - paying double more than what they were offering plus very close to home. Wanted Serco because of the exposure to different project environments.