I was listening to Ben Stein (Economist and Actor) on the radio last week. If I understood him correctly he was suggesting a lump sum target at retirement of 20 times your salary.
He was talking to Americans, but I'd imagine the maths wouldn't be too different for the rest of us, interest rates would affect annuities a bit. That means someone on 40,000 would need to have 800,000 saved, which seems is lower than I would have thought was necessary.
But if we take his figure and go on from there to see what kind of annuity 800,000 could buy, it might give you an idea of whether your Defined Benefit Pension is going to be enough.
He also made an interesting point that isn't made enough. If you live for 20 years after you retire, prices will double in that 20 years. So unless your benefits are indexed linked, or you have the capital to dip into, you're going to be getting progressively more and more broke as you get older.
That mightn't be a problem, most of us will probably wind down the world travel as we head into our 80's.
-Rd