It wasn’t an ideal day for Lynton Crosby to receive his knighthood. If he was a hero of last year’s Conservative general election victory (and he has been careful to take as much credit as possible), his operation has to take a good share of the blame for Zac Goldsmith’s very disappointing defeat in London. Although, as the candidate, Zac must take ultimate responsibility for the campaign he fought, I understand from impeccable sources that he dutifully followed the Crosby-Textor-Fullbrook script.

London is a Labour-leaning city. Remember that, last May, even Ed Miliband did well in the nation’s capital, increasing his party’s vote share by 7.1 per cent when, throughout the nation as a whole, he could only manage a 1.5 per cent increase. So in order to keep control of City Hall, Conservatives needed the independent-minded, bespoke-Tory that has turned the once-Liberal Democrat stronghold of Richmond Park into one of the safest Conservative constituencies to show up. Zac’s climate change views had the potential to win Green voters to his corner. His views on Brexit could have attracted Ukippers. His opposition to Heathrow could have been very powerful across South West London. And, more importantly, his cumulative record of voting against David Cameron in the Commons could have won over the same Labour voters who backed Boris Johnson – and the same kind of Londoners who backed the pre-controversial Ken Livingstone when he ran, 16 years ago, as an anti-Blair, anti-system independent.

None of that Zac shone through. Instead, he fought the same narrowly-themed, centre-right, Boringsville campaign that is Crosby-Textor-Fullbrook’s trademark. The key ingredients are usually tax, competence, negativity about opponents and message discipline. In ordinary circumstances it works because Mark Textor, in particular, is a polling genius and is good at finding candidates’ strengths, opponents’ weaknesses. Crosby then ensures, with his brilliant organisational skills, that the candidate majors upon them. Incessantly. And when you are up against weak candidates like Ed Miliband it can work very well.

In the interests of full disclosure, I’ve said something like this before. In an article for The Times last year, I complained about the Crosby approach to politics. I wrote: “The vision Gove set out in last week’s “warriors for the dispossed speech is the real vision for a Conservative Party that wants to win more than 35 per cent of the vote at the general election. Crosby’s political recipe might be enough to beat Ed Miliband. It’s not enough to build a Conservative Party that deserves to win elections or to stop the decline of faith in our political system.”

I haven’t been forgiven by the thin-skinned Sir Lynton for writing that piece – although I stand by every word of it. A Crosby-ified Toryism can eke out victories against average opponents, but it is no guide to winning well or winning at a time when the capitalist system is being questioned; when Thatcherite and Reaganite orthodoxies are being questioned or when, in such places as Scotland (and now London), the Conservative brand is weak and needs rebuilding.

I don’t think Zac was wrong to ask searching questions about Sadiq Khan’s links to extremists – although the way the questioning began to dominate his campaigning seemed counter-productive. The problem with the Zac campaign was that it was not about him. It was inauthentic. It had nothing of what Ruth Davidson brought to her campaign. She was real on the trail (sometimes too real?!?). She championed a blue collar conservatism, reaching new voters, while being as stoutly Unionist as any Tory has ever been, so keeping the Conservative family together.

The Crosby-Textor-Fullbrook approach has been criticised before. Guto Harri, Boris Johnson’s former head of communications, complained that the 2012 re-election campaign for the now outgoing mayor had taken “the bubbles out of the champagne”, and that Boris’ appeal had been underplayed. Sir Lynton could have fairly countered that a win is a win is a win – even if Boris Johnson’s second victory over Red Ken was only very narrow. But Harri was on to something. There are times for repetitive, monochrome, negative campaigns – but we must understand the limitations of those campaigns. They will not defeat stronger Labour opponents, only weak ones, as my Times article attempted to argue.

While, as now, Conservatives have weak opponents at the national level they none the less shouldn’t complacently tread water. Better candidates will (eventually) succeed the Tories’ dream Corbyn-McDonnell ticket. Conservatives need to dig deeper, and search for a broader, more popular centre-right agenda. Reform of capitalism must be at its heart. Zac was, interestingly, someone who has thought a lot about that broader conservatism. It’s a real shame that Londoners never really got to see that Zac. He should have stood up to the Crosby-Textor-Fullbrook dark knight operation. I think he’ll regret for many years to come that he didn’t.