A starting salary of £100k is totally unrealistic. I would expect a FTSE 100 company (banking) to hire an MBA with a salary of between £30,000 and £40,000. A friend of mine who graduated from Oxford with a 1st in Maths and a Masters in Econimcs and got a job as a corporate investement banker and started on £38,000 and a company car, phone, laptop, free healthcare etc.
3 years on and he is now earning a basic salary of £55,000 but gets upwards of £250,000 in bonuses for completing certain goals. He basically gets 1% of every investment he makes from his clients and most of them invest over £100,000 so the bonus soon starts staking up.
You should see the car he drives, sometimes I think I picked the wrong career! haha