A. You know what? You are worrying about the wrong thing. Yes, it is perfectly possible that you could get knifed not very long after joining an investment bank. Unfortunately that's the way banking is: People get welcomed aboard with fat pay packages when they are needed and axed as soon as they aren't (your age, by the way, wouldn't necessarily be a big factor - younger people get knifed too, warns recruitment expert Tony Tucker).
More to the point, however, we think you will struggle to find a banking job in the first place. Although it is perfectly possible that you could land yourself a job in a bank - if you have some relevant specialist knowledge, the right kind of personal and networking skills, plus a good dose of determination and luck - the brutal truth is that 15 years with a large corporate like Shell is not something that will turn most banks on.
The cultures are too different. Rightly or wrongly, there's a view in the macho, individualistic world of high finance that Shell is a bit like the civil service - good performance well may be required, but it is achieved within the protected environment of a giant bureaucracy that institutionalises employees after a while, and certainly after 15 years.
So, by all means try, but don't expect to waltz into the job of your dreams, and do have a plan B. Also, you should not be looking at associate level jobs. They are aimed at people in their mid- to late-20s or early 30s at the most. Here ageism may well play against you.
Your best chance is to identify an area where you have specialist knowledge - presumably related to the oil and gas sector - and make direct approaches, ideally with the recommendation of a networking contact. As with any career change, you should be aware that networking is your best chance of success.
Good Luck, and do let us know how you get on. We'd love to get an email saying, "You were quite wrong, I had two competing offers within weeks of looking."
Next week's question: During an interview for a job in investment banking, I was asked "Suppose I am the candidate and you are the interviewer. You want to know if I am clever, what question would you ask me?" What are such questions designed to test?
What would you advise? Send your answer to: email@example.com.
Look out for the Experts' answer to this dilemma and readers' comments on Ask the Expert next week. If you would like to submit a question to our panel of experts, ASK THE EXPERT.