All it proved was that David Davis is now a rebel with a cause after he dramatically resigned his seat in order to force a by-election when the Government won a Commons vote to hold terror suspects for up to 42 days without charge.

Instead of sitting on the front bench in the House of Commons as Shadow Home Secretary, he will now be positioned a few rows behind on the backbenches – and with less influence than he commanded before he forced this unnecessary "big brother" election that has cost the public purse £200,000.

In essence, that is the only thing that has changed in the past month.

Davis's campaign in East Yorkshire can hardly be construed as a triumph for democracy, even though there were 26 candidates from the bizarre to the ludicrous.

The fact that neither Labour nor the Liberal Democrats contested this seat denied Davis the credibility that he desired – and the national debate that he sought on civil liberties. The contest was also overshadowed, and understandably so, by people's fears about the economy.

Contrast this with the history-changing nature of the Newbury
by-election of 1993, made famous by Norman Lamont, the then Chancellor, arrogantly declaring 'Je ne regrette rien' over his mishandling of the economy.

This contest attracted a motley crew of 20 candidates – a piece of political notoriety that looked unsurpassable until conspiracy theorist David Icke, Miss Great Britain, the Militant Elvis Party and others decamped to these parts.

But Newbury had seismic repercussions because the collapse of the Conservative vote in its "shire" heartlands effectively confirmed that John Major's Government was dead in the water.

It was also the by-election where tactical voting proved decisive. Because people switched to the Lib Dems in their droves, Labour's vote was squeezed to two per cent – a share of the turnout which was even lower than its spectacularly poor showing in Henley recently when the party limped home in fifth place behind the Greens and BNP.

The only consolation for Gordon Brown was that Henley – the seat vacated by Boris Johnson when he became Mayor of London – has never been natural Labour territory. An elephant would have won for the Tories, provided it had a blue rosette on its trunk.

The same cannot be said for Glasgow East – the next destination for the by-election circus and a contest that may ultimately change the future direction of the country, in contrast to Mr Davis's exercise in self-worthiness.

It is Labour's 25th safest seat in the country, even safer than Crewe and Nantwich where last month the Tory Party's first by-election gain in a generation confirmed David Cameron's political resurgence.

If Mr Brown cannot hold Glasgow East – a seat which returned Labour's first minister of health in 1922 and where 120,000 people descended upon the station to serenade John Wheatley aboard the train to Westminster – then the discontent about his leadership will quickly turn into a torrent.

And it must be remembered that the demographic make-up of the seat – the male life expectancy rate on one notorious estate is lower than
the war-torn Gaza Strip – should favour Labour.

These are the people who are supposed to have benefited most
of all from Brown's stewardship of the economy and crusade
against poverty.

Yet the omens are not good as the Scottish Nationalist Party's campaign gathers momentum. The fact that Labour struggled spectacularly to select a candidate does not bode well. If you're the Labour MP for Glasgow East, it's the closest thing in politics to a job for life.

I suspect that the reason several candidates fell by the wayside before Margaret Curran volunteered her services was that they did not want to be associated with Brown in case any electoral disaster limits their future career prospects.

Indeed, I note that the PM – who has no plans to visit Glasgow – is not even mentioned on Ms Curran's campaign website.

Boundary changes, and the fact that the poll is taking place during the middle of Glasgow Fair, the traditional two-week trades fair when Glaswegians head off to the coast, make this result even harder to predict (that is if families can even afford a break in these austere times).

If Labour performs badly, Brown will attempt to blame the political bounce that the pro-independence SNP is still enjoying after taking control of Holyrood, and Labour's own internal difficulties north of
the border.

However, while it is not uncommon for governments to suffer by-election reverses of varying degrees, history is now against Brown.

No PM has recovered from such a bad set of poll ratings to win the next General Election; not even Margaret Thatcher sought to brush aside the result of Eastbourne by-election of October 1990 when the Liberals Democrats overturned a 17,000 majority, thanks to a 20 per cent swing.

Within six weeks, Thatcher had been ruthlessly removed from office by senior Conservatives who realised that the time was up for their
leader when they could no longer take "true blue" seats like Eastbourne for granted.

The defeat was even more marked because of the sentimentality shown towards the Government at the time; the by-election had, of course, been forced after the IRA assassinated Thatcher loyalist Ian Gow.

It remains to be seen whether an electoral setback in Glasgow East – where the SNP need a 22 per cent swing – will have the same repercussions for Brown. But he should be aware that defeat here would be on the par with the Conservatives' humiliations in Eastbourne, and then Newbury.

Like Thatcher did in 1990, I suspect that the PM will limp on rather than take the opportunity to resign with a degree of dignity "for the sake of his family".

However, such entrenchment would mean the repercussions of the Glasgow East result on July 23 dominating the political agenda until the party conference season – far more so than David Davis's vanity exercise.

It is this autumn when the so-called "men in grey suits" are most likely to ask the Prime Minister to step aside when they realise that the Labour Party is a lost cause when they cannot prosper in areas like Glasgow – or raise funds to bankroll future election campaigns because of Gordon Brown's unpopularity.

That is why Glasgow East matters far more than Haltemprice and Howden. The voters of this one constituency will potentially have the future of this country in their hands when they go into the ballot booth.