A scandal that lifts the lid on the seamier side of spin

<b>Leading article:</b> If McBride's briefings were widely known in No 10, more heads will roll

The big question facing the Prime Minister following the departure of his disgraced adviser is: did others in Number 10 have any idea of what Damian McBride was up to? If other senior officials, let alone the Prime Minister, are shown to have had the slightest inkling of the depths to which Mr McBride was taking the word "spin", the scandal over his emails directed at senior Tories will not be solved by his departure alone.

Let us assume – and hope – that Mr Brown, in all his frantic activity, had no detailed knowledge of the kind of loathsome campaigns in which one of his closest aides was engaged. But the Prime Minister remains damaged by this scandal. Mr McBride was part of a small team of ultra-loyalists who have surrounded Mr Brown since he became chancellor, making many enemies in their energetic defence of him. The Prime Minister knew that Mr McBride was an unmanageable attack dog and had been warned that "McPoison", to quote his revealing nickname, was a liability.

Despite this, Mr Brown's clannish, suspicious instincts prevailed. He had the opportunity to dispatch Mr McBride last year, when his then media adviser briefed journalists about Ruth Kelly's forthcoming resignation "to spend more time with her family" – while she slept. But instead of getting rid of him, he shuffled the deck, moving Mr McBride from media to strategy – a backstage arena in which the temptation to dabble in the darker arts of spin seemed greater than ever.

Now Mr Brown must face the consequences of his mistaken loyalty. The vaunted "new era" of Brown government, supposedly marked by more transparency, less control freakery and, above all, less spin, has been exposed – though not for the first time – as a total sham. Of course, politics is all too often a dirty business. And Mr McBride is not the first government adviser to touch on politicians' personal lives in briefings against the opposition. But this sort of smearing is different to the spin that surrounded Tony Blair and Margaret Thatcher. This is the lowest sort of politics, inventing sleaze to smear opponents – even their partners – in the pursuit of political advantage. To dismiss this as merely "juvenile" is insufficient.

Apart from the question about whether others in Number 10 were in the loop about the strategy adviser is a separate, albeit related, issue. Mr McBride was pursuing highly partisan political activities on taxpayers' money, breaching civil service rules. Amid the hullabaloo over the content of his emails, we must not forget that he was not paid for by the Labour Party. He was a seconded civil servant, paid, handsomely, out of our pockets. If it achieves nothing else, we must hope that Mr McBride's departure again focuses attention on the way the dividing line between civil servants advising the Government and people on the public payroll spinning for the Labour Party has become blurred over the last decade.

Ultimately, the McBride affair does more than reflect badly on Mr Brown and his secretive, sectarian and cabal-ridden style of government. It further damages the public reputation of Parliament and of the British political class at a time when they can least afford it. From Lords asking questions for cash, to MPs claiming expenses for holiday homes and satellite pornography, to the McBride scandal – it's a rotten trajectory. In spite of what some say, ours is not yet a society in which the words politics and politician should evoke automatic contempt. Many members of Parliament remain deeply honourable in their intentions. But once again, politics has been dragged into the gutter, and this time it is Downing Street itself involved. For this alone, the McBride affair is a sorry reflection on Mr Brown's term in government.