Last night I voted Liberal Democrat in a by-election for Bromley council. The vacancy, in Crystal Palace ward (formerly Anerley), arose following the death of the long serving incumbent, Chris Gaster. He put 36 years of service into our community.

It is people like Chris Gaster, and his team, still pounding the streets delivering Focus leaflets, that kept the party going in difficult times. I sometimes wonder, having observed a few at close quarters, if extreme adversity makes them redouble their efforts.

I'm not sure the same can be said about those at the top of the party. Adversity is descending again on the Liberal Democrats. The Independent's poll of polls puts them on 16 per cent, well down on the 2005 general election showing of 22 per cent, and the more worrying because of the Tory revival, halting as it is.

It points to a big swing from the Liberal Democrats to the Tories next time, and lots of lost seats. Even if the Liberal Democrats hold the balance of power they will not be able to press home that advantage because a denuded parliamentary group will lack any moral authority when it comes to making demands of Labour. Worse still, the party's brightest and best may lose their seats, and be in no position to challenge Ming Campbell for the leadership. They should know that, and act accordingly to save themselves and the party.

The most urgent change to make is at the top. This isn't because Sir Ming Campbell is too old. That wouldn't really matter if his leadership were making an impact. It isn't.

Internally you get the impression that he spends his time lunching with a friend called complacency. Paddy Ashdown could get frustrated to the point of rage with the party, but he never gave up poking the little furry things with a stick every so often, just to make life more interesting. Sir Ming doesn't seem that interested in his party.

Externally, I just wonder what the Liberal Democrats will have left to "sell" now Blair's gone and when Brown pulls the last soldier out of Iraq.

I know it's tough when Cameron (the environment) and Brown (everything else) keep nicking your best ideas. But I do yearn for someone on the national as well as the local level to answer the question: "Why Lib Dem?"