When the party faithful try to lure young, unsuspecting victims to join their ranks, they use a well-worn mantra as a draw: you can make a difference. Be elected MP (or councillor or mayor) and ordinary folk will eat/feel/sleep better - or safer. Oh, what a wonderful legacy.
If we measure a politician's success by this yardstick, the late Barbara Castle was a giant among her peers. Thanks to the Red Queen, we have equal pay, seat belts, breathalysers, child benefit paid directly to mothers, and earnings-related pensions (or we did until the Tories scrapped them).
Many of these measures were vigorously opposed when Castle first mooted them. It was only because the feisty minister remained unwavering in her conviction and became personally associated with every one of the proposals that they were finally adopted as legislation.
How many of today's ministers can claim to have made this kind of impact on the everyday life of Britons? New Labour can boast some splendid achievements: devolution, the disbanding of the hereditary peerage, the minimum wage, the independence of the Bank of England, the Northern Ireland peace accord. But these changes were made by - and are associated with - the two men at the helm, Tony Blair and Gordon Brown. It is hard to think of other new Labour ministers who have become personally associated with specific measures that have improved ordinary people's lives. David Blunkett's numeracy and literacy hours, introduced when he was at Education? Perhaps. But will they survive another 30 years? Harriet Harman's determination to get better childcare? Still unfinished business.
You need to be brave to nail your colours to a particular issue: as Castle herself found out with her proposals for trade union reform, commitment can sink your reputation as much as build it. Today's politicians prefer the headline-grabbing initiative, here today, gone tomorrow; they seem to shrink at the first sign of opposition to a solid proposal. There is another explanation. Harold Wilson proved self-confident and generous as Castle's PM. He gave her free rein to put her stamp on the things she cared about. In today's anxious, spin-doctored climate, ministers are allowed less room for manoeuvre and individuality. Castle would not have survived in the present cabinet. We would have been the poorer for that. And less safe. And less equal.