By declining to put up an official candidate to fight the Richmond Park byelection, the Conservative party has shown itself to be cynical, cowardly and rational. It took the decision knowing that it is not a great look for the governing party to absent itself from the contest. It calculated that it would be an even more dreadful look to field someone in the colours of Mrs May and see them slaughtered. Which is what would have happened. The chances of an official Tory candidate winning in this leafy patch of southwest London would have been somewhat lower than a flying saucer piloted by Elvis and Lord Lucan landing on the head of the Loch Ness monster.

There is no constituency in the country with a more intense concentration of rage about Heathrow expansion and the government has just declared that it wants to multiply the number of planes flying over its rooftops. The constituency voted heavily to remain within the European Union and the government is embarked on a trajectory towards one of the harder versions of Brexit. A candidate in the name of the Tory party would have split the Conservative vote, enhancing the chances of the Lib Dems taking the seat. So cowardice and cynicism combined with logic.

Yet this does not mean that the absence of an official competitor for the Tory party is an unalloyed blessing for Zac Goldsmith, the former Conservative MP who is recontesting the seat in the guise of an “independent”. Once upon a time, when he had a reputation as someone who was not enslaved to his party’s line, he might have been convincing in that role. Not now. Only a few months ago, he was the Conservative candidate for mayor of London. Moreover, he made the disastrous decision not to run on his own terms, but to be the frontman for a racially charged campaign designed by the Tory machine. Both nasty and ineffective, even his sister, Jemima Khan, was moved to publicly deplore that campaign.

Only very occasionally in British politics have we seen genuine independents in parliament. One such was Martin Bell, the former BBC correspondent famed for his white suit, who ran and won as the anti-sleaze candidate against Neil Hamilton in Tatton at the 1997 election. Zac Goldsmith is no Martin Bell. To see how truly independent he is, we only have to visit the website of the local Tory party. When I checked there on Saturday, the banner at the top of the home page still featured his mugshot alongside the Tory logo. The strapline read: “Supporting Zac Goldsmith in the Richmond Park constituency.” The video content is a stream of images of the man who is supposedly no longer a member of their party. A statement by the chairman says that “the association and its resources will not play a part in this byelection”, before declaring that “individuals who are members of the association may well wish to support Zac’s campaign and they are at liberty to do so”. It then provides an email address for joining his campaign.

Statements from the Tory party nationally have conveyed their warmest wishes for his re-election. Should he be returned as an MP, it is widely suspected, and he has not denied it, that he will only sit as an independent for a while before, after an interval he judges to be decent, rejoining the Tory party. If words in politics retain any meaning, Zac Goldsmith is no independent. If he is re-elected, it will be a message to Mrs May to carry on as you are.

It is a big challenge to run as a genuine “independent” because they can’t usually compete with the money, logistical capacity and activist base at the disposal of organised parties. I guess the money is no obstacle in this case. The trustafarian Mr Goldsmith has exceedingly deep pockets. There is an issue over how much support – overt or clandestine – he is going to get from the Conservative party. Will the Tory machine feed him with voter data? This is a highly valuable commodity, especially at a byelection when turnout is often pivotal to the outcome. It seems to be a legal grey area whether the Tory party can gift him resources without it counting against the byelection spending limit or whether he should be expected to pay a commercial rate and count that as a campaign expense.

He starts with some significant advantages. He has a well-known name, enjoys the benefits of incumbency and won a chunky majority of more than 20,000 in 2015. The first opinion poll – for what it’s worth – has him comfortably ahead. In an age that expects politicians to betray their pledges when they become inconvenient, he may earn credit with some voters for keeping his promise to resign and recontest the seat if his party went ahead with Heathrow expansion.

Here, though, is a paradox. This byelection may have been triggered by the runway decision, but it is essentially irrelevant to the contest. His Lib Dem rivals are just as opposed to the expansion of Heathrow and, unlike Mr Goldsmith’s party, they have always been united in their conviction that it is a terrible idea.

The Lib Dems, who came second in the seat in 2015 and held it until 2010, ache for the boost in media attention and party morale that they would receive from a victory. Vince Cable suggested that he might be up for attempting a comeback there, but in the end he did not apply to be the candidate. It concerns some Lib Dems that their flagbearer, Sarah Olney, lacks the name recognition and the experience of her opponent, but that has not prevented them from pulling off byelection sensations before. Tim Farron’s party seeks to cast the contest as a referendum on the Tory government and particularly its trajectory towards a hard Brexit. This makes sense. If they are to see a national revival from their near-death experience at the last general election, a good hunting ground for the Lib Dems is among Remain voters alienated from both a Brexiteering Tory government and Corbyn Labour.

On Europe, Labour is split and scared about how to deal with the division between its London stronghold, which voted heavily for In, and its Midland, northern and Welsh heartlands, where there was hefty support for Out. That prevents Labour from being a clear voice for “the 48%”. The Lib Dems don’t have that difficulty. They can be unequivocal opponents of hard Brexit. They believe that helped them to do well at the recent Witney byelection where they leapfrogged from fourth place to second, with a swing of 19%. The swing to them from the Tories would only have to be a smidge higher for the Lib Dems to take Richmond Park. Mr Goldsmith is at odds with most of his constituents, who voted by more than two to one to remain within the European Union. It is probably not to his advantage that he is so to the liking of Nigel Farage that Ukip has stood aside from the contest and endorsed him. In such an anti-Brexit constituency, it is of dubious benefit to be the lightly camouflaged candidate of the Tory party and the explicit candidate of Ukip.

Some hoped that Richmond Park might be a testing ground for the idea of a “progressive alliance” between parties on the other side of the spectrum. Three relatively senior Labour figures, Clive Lewis, Lisa Nandy and Jonathan Reynolds, last week jointly suggested that their party should stand aside to maximise the chances of a Lib-Dem victory, on the grounds that “in this parliament progressives will need every vote that they can get”.

This was an interesting intervention and the more so because the trio hail from different wings of the party. Their initiative might even deserve to be called quite brave, for committing the heresy against tribal gods of suggesting that sometimes people should support a party other than their first choice. The idea has got nowhere because it received a predictably icy response from the party leadership. Jeremy Corbyn and his deputy, Tom Watson, don’t agree on much. On opposing this idea they are as one. Caroline Lucas, the Greens’ only MP, is one of the more eloquent advocates of deeper co-operation between non-Tory parties. She visited the Richmond Greens to see if they might be persuaded to stand aside and found them unwilling. She concluded: “The old politics dies hard.” Sure does. This episode is a lesson to the advocates of a progressive alliance about just how hard it will be to turn the concept into something meaningful.

So there will be Labour and Green candidates contesting Richmond Park, even though they don’t stand a hope of winning. This may not ultimately matter. If the Lib Dems can get one of their bandwagons rolling, they will put a hard squeeze on support for the also-rans. The British electorate has a lot of experience of byelections. They understand the dynamics and act accordingly. Richmond Park has the highest proportion of university graduates in the country. They shouldn’t have much problem grasping the concept of tactical voting. Nor should they have much difficulty spotting the difference between a genuine independent and a fake.