In “At Bertram’s Hotel”, Agatha Christie immortalised her fellow writer, G.K.Chesterton, with am amusing anecdote: “Ever heard that story about Chesterton? G. K. Chesterton, you know, the writer. Wired to his wife when he’d gone on a lecture tour   ‘Am at Crewe Station. Where ought I to be? “

While pondering the by-election verdict of the voters of Crewe and Nantwich, Gordon Brown should be asking himself the same question: “where ought I to be?” On current performance it will not be 10 Downing Street.
After bad local and London mayoral elections, followed by Crewe, the Government’s propagandists predictably dismissed the Crewe result as mid-term blues. That simply isn’t plausible.
By-elections are probably the best barometer we have for reading the political weather.
In recent years there have been far fewer by-elections. This is because of the younger age of MPs and, with secure pensions for the older ones, there is more willingness to retire rather than be carried out of the Commons in a box.
During the 1970s and 1980s by-elections occurred far more frequently and they regularly led to the governing party getting a bloody nose.  These electoral upsets – from Sutton to Ribble Valley – didn’t necessarily mean that come a General Election everyone would vote as they had in the by-election and seats frequently reverted.  The smaller parties – especially the Liberals – were frequently able to snatch a by-election but they themselves joked “we know how to win them and we know how to lose them”.
And, like the proverbial arrival of the early swallow,  one by-election victory doesn’t necessarily make a government.
In 1979 I won a by-election victory in Liverpool, taking a “safe” Labour seat. The swing was 30% and I took 64% of the vote. The Conservatives lost their deposit. Four weeks later the Conservatives became the Government and my party – the old Liberal Party – held just 11 seats, although happily mine was one of them.
By-elections give people a rare opportunity to “take a chance” by voting for a party or candidate of a different political persuasion. They know that whatever the result, it won’t change the government (at least, not yet).
A by-election is a chance to send politicians a message; to put them on notice. Local grievances often dominate; while the personality of candidates – who is going to be your MP – is much more of an issue than at a General Election  when voters think more about who will run the country rather than who will speak for them in Parliament.
By-elections are also an opportunity for individual candidates to shine, to cut their teeth and to make their reputations. Winston Churchill contested no less than five parliamentary by-elections; Tony Benn four; Roy Jenkins two; and Betty Boothroyd three.
And who can ever forget the inevitable intervention of colourful fringe characters such as Screaming Lord Such and Bill Boakes – bringing a sense of the absurd to our portentous proceedings?
But, occasionally, a by-election occurs that is a real harbinger of a seismic shift in political mood and allegiances.
In 1938 the famous Oxford by-election campaign was dominated by the issue of appeasement.  Following the agreement reached with Hitler at Munich, by Chamberlain’s Conservative Government, the Liberal and Labour parties united around an anti-appeasement candidate. He failed to win but, as they say, the rest is history.
After the War, the Orpington by-election of 1962 – which led to the sensational defeat of the Conservative candidate by the Liberal, Eric Lubbock, on a 26% swing – was certainly another defining by-election.  Harold MacMillan’s Conservatives no longer looked unassailable and two years later they lost the General Election. It also led to the rebirth of the Liberal Party under Jo Grimond’s leadership.
In 1981, the Crosby by-election, which Shirley Williams won for the SDP with 28,000 votes (41%), was another defining moment in politics. It gave huge momentum to the Liberal-SDP Alliance and led to a calamitous result for Michael Foot’s Labour Party in the 1983 general Election.  That, in turn, forced Labour to reform and renew itself .
The by-election experience of a young Labour candidate, Tony Blair, hastened that process. In 1982 , on Michael Foot’s manifesto,  he contested the Beaconsfield by-election. He saw the Labour vote halved and he lost his deposit.
By-elections can set alight political dreams but they can also deliver a fatal blow.
By an odd quirk, in 1990, a by-election in Bootle, the seat adjacent to Crosby, was also definitive. There, the SDP polled just 115 votes (0.4%) and ceased to exist as a political force.
Seven years later, as Labour donned the SDP’s clothes, another Merseyside by-election, in Wirral South, was handsomely won by Tony Blair’s New Labour. It demonstrated that John Major’s days in Government really were numbered and that Labour was once again electable.
Crewe falls into precisely the same category as these defining moment by-elections. It is no “flash in the pan”. It is a harbinger by-election predictive of change.
Crewe is the first constituency that David Cameron’s Conservatives have taken from another party in a by-election in three decades – and it is in the north of England, not a region friendly to Conservatives of late.
Crewe is also  indicative of a fundamental change in mood and voting intentions.
No doubt in achieving this disastrous result the condition of the economy, and the ten pence tax band fiasco played their part – along with Labour’s absurd reopening of “class war” and the stirring of immigration and race – but it goes deeper than that.
As Labour and the Liberal Democrats (who will now presumably sack Nick Clegg and bring back Ming Campbell or Charles Kennedy) consider their loss of votes, let them also remember that voting took place two days after Parliament voted on abortion time limits, animal human hybrid embryos, saviour siblings and a child’s need for a father.
Millions of people, beyond Britain’s five million Catholics, have been deeply shocked by the outcome of those votes.
In the early 80s millions of these same quiet voters switched their allegiances from Labour to the Liberal-SDP Alliance. In the late 1990s they felt able to vote for Tony Blair. Now they are quietly transferring their votes to David Cameron’s Conservatives.
If Mr.Brown is now pondering Chesterton’s fictional question to his wife from Crewe railway station: “where ought I to be?” he needs to understand that he has opened a yawning chasm between himself and many ordinary people.  He has become disastrously disconnected from people who would previously have voted for him and his party.
These ordinary quiet voters are brilliantly described by Chesterton as “The Secret People” and the final lines of that poem warns our political masters against  utter disregard for the beliefs and wishes of this country’s ordinary, secret, people:
“But we are the people of England; and we have not spoken yet.
Smile at us, pay us, pass us. But do not quite forget.”