Michael Brown: Failure of Cameron's pet candidates will strengthen his opponents' hand

The Tories have both "won" and "lost" this general election. Mr Cameron has the strongest mandate in terms of seats and votes. Whatever machinations take place over the coming days, it is still likely that, by the time Parliament meets, David Cameron will be Prime Minister and will present a Queen's Speech to the House of Commons on 25 May.

It remains, of course, to be seen whether Mr Cameron's offer of discussions with the Liberal Democrats results in a coalition. And if they fail, will Nick Clegg still allow the Tories to form a minority government? It all depends on whether Mr Clegg is intending to use political reform as the sole deal breaker with the Tories. Meanwhile Mr Brown will continue to squat in Downing Street – as is his constitutional right – dangling the carrot of a referendum on electoral reform under the nose of Mr Clegg.

But Mr Cameron has gained over 90 seats and polled two million more votes than Labour. He claims this is the largest number of seats gained in a single general election, by the Tory Party, since 1931; while Labour has achieved one of the worst results in its party's history. But this is a pyrrhic Tory victory. In the words of one senior Tory backbencher to me yesterday, "Cameron has pissed this election away." The Tory leader has spent more than four years "decontaminating the brand". Yet, against this backcloth of humiliation for Labour, he has ended up with less than a 3 per cent increase on the share of the vote achieved at the 2005 general election by Michael Howard, who pursued a "dog whistle" campaign highlighting, immigration, Europe and tax cuts.

This result is a recipe for Tory backbench recriminations that could poison Mr Cameron's putative premiership from the start. Particular embarrassing for the leadership were the heavy defeats for the likes of Shaun Bailey, the black candidate in Hammersmith; Joanne Cash the über Cameroon, who described her party workers in Westminster North as "dinosaurs"; and Mark Coote, the openly gay candidate in Cheltenham. These three were the poster boys and girl for the "modernisation" campaign that consumed Mr Cameron's energies when he could have been formulating coherent policies to address the economic crisis and the national deficit.

Most, though not all, Tory backbenchers, whether friend or foe of the party leader, would rather be in government than in opposition – but not at any price, and certainly not (wrongly in my view) at the price of sacrificing the first-past-the-post electoral system. This will tie the Tory leader's hands in any discussions he may have with Nick Clegg. The Tory blogger Iain Dale has suggested that Mr Cameron could offer Mr Clegg legislation on a referendum for PR – and then promptly campaign for a "no" vote. Somehow, I suspect such Machiavellian tactics would cause mayhem in the Tory ranks.

Should he cross the threshold of No 10, Mr Cameron will face as many nightmares from behind him as he will from the parties ranged opposite him. He will be under pressure to dispense with the "voodoo advisers", led by Steve Hilton, who have sought to control and sideline backbench MPs, parliamentary candidates and the party membership. As Harold Wilson recognised throughout his minority government premierships, the only place that now matters is the House of Commons and the parliamentary arithmetic.

The outgoing chairman of the Public Accounts Committee, Edward Leigh, said that while the public have punished all the political parties "they have reclaimed the House of Commons for every Member of Parliament".

He continued: "The power of the executive has been diminished while the supremacy of the House of Commons will now be enhanced – every backbencher is now a player."

The post of Tory chief whip will assume as great an importance as that of Chancellor. Fortunately, Mr Cameron is well-served by Patrick McLoughlin, the former miner, who has served in the opposition whips' office since 1997. But his patience, even temperament and good judgement will be sorely tested.

The focus of Tory backbench attention will centre, initially, on the vacant post of the chairmanship of the 1922 Committee – the spokesman for the parliamentary party to the leadership. The contenders, Graham Brady, Nicholas Soames and Richard Ottoway, will be furiously lobbying the 150 or so newly elected MPs. Mr Brady is seen as the right-wing candidate – he resigned in 2008 from the front bench over his support for more grammar schools – and a victory for him would be the harbinger of party disunity from the start.

One thing is for certain, and that's that speculation on the date of the next general election will begin this weekend.

It's hello to...

Jo Johnson

Low-profile younger brother of Boris, who won Orpington in south-east London.

Kwasi Kwarteng

Ghanaian origin, Eton- and Cambridge- educated, won in Spelthorne, Surrey.

and goodbye from ...

David Heathcoat-Amory

Lost in Wells, Somerset, after 27 years. Had paid back £30,000 in expenses.

Nigel Waterson

Shadow pensions minister, and junior minister under John Major, lost Eastbourne after 18 years.