GP_flagCaroline Lucas is this country’s Great Green Hope, and it’s a very unwise Green Party member who seeks to get into a public argument with her. But I think it’s essential to challenge her view (Guardian, 17 June) that the best way to put Green policies into action is by entering into electoral pacts with other ‘progressive’ parties.

We have just fought a General Election during which we exhorted people to ‘vote for what you believe in’. We didn’t suggest that people ‘vote for the least-worst alternative’, or ‘vote Labour if they’re neck-and-neck with the Tories’. We put up candidates in over 90% of constituencies in England and Wales in order to give voters the chance to support our manifesto, which was based on well-thought-out policy proposals reflecting our core values and beliefs.

The fact that our electoral offer did not lead to an increased number of Green Party Members of Parliament is a great shame, of course. It’s partly (as Caroline points out) a consequence of an undemocratic electoral system that’s stacked against a party whose support is thinly spread. Partly it’s down to a lack of clarity in the story we told the electorate; and, if we’re honest, some of the blame must lie with flaws in our election strategy.

Our failure to gain more MPs to join Caroline in the Commons is a setback that should inform future tactics and encourage us to build a more effective political machine. What it shouldn’t do is start a debate about our continued existence as a distinct political force – which is what talk of pacts, however cautious, will tend to do.

Yes, we should vote and work on particular issues with people from other parties when their views coincide with ours. We should – for example – have the courage to join our voice with UKIP’s when they call for proportional representation. We needn’t worry that their brand will taint ours, simply because electoral justice would benefit us both.

What we shouldn’t do, in the wake of electoral disappointment, is make any moves which risk diluting our principles, our integrity, and ultimately our effectiveness.

A pact between such unevenly matched forces as the Green Party and Labour, or the Greens and the SNP, would be a one-way ticket to political oblivion. It would confirm what our enemies have always sneered: that we are nothing but a pressure group. Many pressure groups do fantastic work, and our society would be poorer without them. They seek to nudge, shame and influence. But they don’t seek to gain political power. That is what political parties exist to do, and that must continue to be the aim of the Green Party.

Anything else will suggest to people in other parties – ones we may have much in common with, and ones to which we’re profoundly opposed – that we have quit the field of battle.

From the perspective of a party with hundreds of MPs, a pact with a party with one MP is a chance to inoculate yourself cheaply against arguments that might otherwise be levelled at you, if that one MP was still a free-ranging, independent voice, inspired by her party’s philosophies and policies, and answerable only to them.

Caroline writes that ‘.. many Labour or Lib Dem candidates wouldn’t get approved by a Green Party meeting …’

I suspect that’s a giant understatement. Like (I would guess) most members of the Green Party, I’m not very interested in making the Labour Party a little bit greener, or the Liberals a little more honest. If individuals within those parties, or any other party, wish to lend a hand to improving the world by tackling climate change and ending humanity’s fatal addiction to consumerism, then they will join us.

The General Election result was very disappointing for Greens – so let’s learn from it. Let’s be smarter, use our people better, tap into all the positive energy that’s out there looking for a home.

We’re supposed to be offering something new and revolutionary, aren’t we? Do we have so little confidence in ourselves, and so little respect for our tens of thousands of members, many of whom are full of optimism and up for a fight (these are not exhausted battlers, weary from a thousand campaigns), that we’re now prepared to help mainstream parties tick the ‘eco’ box?

I’m sure this is not what Caroline intends by her very sensible-sounding proposal; it’s just that like many sensible-sounding proposals, it contains a trap.

The idea of a Green-Lab pact brings to mind all kinds of analogies, but what it most sounds like is a fable: The Mouse Who Married An Elephant.

All kinds of promises are made at the altar, but the results in the marriage bed are all too predictable. Whether by accident or design, the so-much-smaller partner ends up getting squashed …

Roy Bacon is Policy Coordinator for the London Green Party and is running for the London Assembly List.