The five ways that the Remain alliance could derail Boris Johnson

Adored by hikers, endured by the soldiers who train there and admired the world over, the Brecon Beacons are, it is said, named after ancient beacons lit to warn of impending attacks.

These days, this national park is also a Dark Sky Reserve, as famous for its lack of light as for the beacons which once broadcast their fiery warnings over this handsome hunk of Wales.

But the Beacons – and Brecon and Radnorshire in particular – are now sending out a new warning signal, and this one is political.

This week, Plaid Cymru announced it was stepping aside in the Brecon and Radnorshire by-election, as the Green Party has already done, to give the Liberal Democrats the best possible chance of winning this traditionally marginal seat back from the Conservatives.

The reason, of course, is Brexit. In Brecon and Radnorshire, pro-European voters will now congregate around the Lib Dem candidate, Jane Dodds, though at the time of writing we still don’t know the Labour candidate’s position. Pro-Brexit voters will have to decide between Conservative candidate Chris Davies – recently convicted over false expenses claims – and Des Parkinson of the Brexit Party.

Leaders of the anti-Brexit parties have all suggested that this Brecon alliance could be repeated elsewhere in the event of a general election or a new Brexit referendum.

That is a suggestion that should have both Conservative and Labour politicians quaking in their hiking boots. After three years of division, in-party fighting and a quite remarkable lack of progress, the main two parties are about to learn the hard way that politics is changing quickly.

A positive alliance between smaller parties now presents a chilling challenge to both Labour and Conservative MPs. Conservatives may respond with their own lashed-together version of an alliance with Nigel Farage – though it is he who will be the puppet master in any such relationship.

Alliances, though, come in many different flavours. They can range from a basic sense of cooperation, to a full scale pre-negotiated coalition as happened in the early 1980s between the SDP and Liberal Party. In 1997, an electoral pact was formed between the Lib Dems and Labour when both stood aside in the Tatton by-election, where the independent candidate Martin Bell defeated the sleaze ridden Conservative MP Neil Hamilton. Despite examples of successful cross party working, some politicos remain resistant to them. To assuage the concerns of sceptics, here are five other partnerships, of varying degrees of cooperation, to illustrate how many tools are at the disposal of political organisations that decide to work with one another for the greater good.

The non-aggression pact

The parties all field candidates, but only one is fighting (and spending money) for victory. This can be easier for activists to swallow than more restrictive alliances. Think of the 1997 Lib-Lab pact. Campaign directors swap information including target lists and while still fiercely competing in seats where both are in contention, they didn’t focus resources in each other’s marginals with the Tories. The political spinners whirred in to action. In 1997, a spinner leaked to the Mirror newspaper a list of 22 seats where Labour voters would be urged to back the Lib Dems, in a bid to defeat the Conservatives. The plan worked in 20 of those seats. The alliance had worked.

The local cluster

Think of South-West London Greens and Liberals in 2017. This bottom-up approach can help work around national leadership intransigence, and deliver a desired result via a local level alliance.

Tactical voting

In areas where parties have not managed to negotiate a formal pact, the electorate can still swing a result by voting not for their first preference of candidate, but for the candidate best placed to prevent an undesirable outcome.

The simple pledge

Individual candidates can sign a pledge. For example, promising to back Remain in a final say referendum, which could inform a tactical vote

A joint policy commitment

Without standing aside, this allows parties to increase their chances of achieving particular policy outcomes, such as guaranteeing a Final Say vote on Brexit.

What’s important to recognise is that these are all positive alliances – parties get involved because they want to help one another achieve particular goals. They need to be informed by the most up to date polling, but not driven entirely by it – incentives for smaller parties to join in come in the form of real reciprocation and the chance for them to increase their parliamentary clout.

It is also important to note that in order to achieve a stop Brexit majority in parliament, joint working may only be required in a third of the seats up for grabs, perhaps fewer. Beware partnerships that appear to be positive alliances but are actually built on mutual distrust or worse. Boris Johnson and Nigel Farage, we're looking at you.

Naomi Smith is the CEO of Best For Britain, which is campaigning to keep Britain in the EU