Well it depends like I said. If they suspect he has been making additional contributions to a pension, could they go after that money? I don't know - I am not a lawyer and not an accountant. However, a £600k pension pot for a highly paid man at the age of 61 does not seem out of the box unusual to me in any way. Would imagine it would also depend on what other assets he has in terms of savings, premium bonds, house, cars etc - those are easier to go for before starting any complex investigation into pensions.