Alex Salmond is one of the most significant political figures of recent British history, whose tenure as first minister of Scotland transformed the debate about the UK’s constitutional future.

In less than a decade, Salmond succeeded in normalising the question of Scottish independence, rebuilt the Scottish National party into an electoral machine that has convincingly replaced Labour as Scotland’s dominant political force, and laid the groundwork for significant new powers for its devolved government and parliament.

News of the charges against him will send shockwaves through his party and its current leadership. Although his influence has diminished markedly since he lost his House of Commons seat in 2017, Salmond still commands significant levels of loyalty among its activists and SNP parliamentarians.

Facebook Twitter Pinterest Alex Salmond speaking outside the court of session in Edinburgh earlier this month. Photograph: Jane Barlow/PA

Many of them have supported him after the disclosure that the Scottish government had investigated complaints against him. When he launched a crowdfunding campaign to back his legal action over the government inquiry, he raised more than £100,000 from more than 4,000 people in a matter of days.

On 7 January, after months of insisting it would robustly defend its handling of the claims, the Scottish government admitted in an emergency court hearing it had botched it.

Leslie Evans, Scotland’s chief civil servant, acknowledged the official charged with handling the formal inquiry had met the complainants before they officially complained.

Evans insisted that the outcome did not “have implications, one way or the other, for the substance of the complaints or the credibility of the complainers”, but acknowledged that prior contact was unlawful and gave the appearance of bias.

Facebook Twitter Pinterest Salmond and his wife, Moira, after he was voted in as first minister in the Scottish parliament in May 2007. Photograph: David Cheskin/PA

Salmond had become the first SNP first minister in 2007, winning the Holyrood election by a single seat over Labour, with bullish promises to re-energise the Scottish government, making bold offers to abolish student debt and cut local taxes.

Facebook Twitter Pinterest Alex Salmond during a visit to Pennan, Aberdeenshire in May 1999. Photograph: Owen Humphreys/PA

By then an SNP veteran, it was Salmond’s second stint as leader. He had led the SNP through the 1990s when it was a minor political force with just six MPs. He resigned in 2000, for reasons which remain poorly understood, but came back as leader in 2004, to recast his party as a far more disciplined, focused force.

Facebook Twitter Pinterest Salmond celebrates with the new deputy SNP leader Nicola Sturgeon after as he was declared winner of the SNP leadership campaign in Edinburgh in 2004. Photograph: David Cheskin/PA

Running a minority government with a one-seat advantage forced Salmond into delicate parliamentary alliances at Holyrood, most notably with the Scottish Conservatives. Their horse trading over police numbers, business rates and drugs policy meant the Tories backed Salmond at budget time.

Confronted with an adept and combative SNP leader, Scottish Labour imploded, losing a series of Holyrood leaders, and found itself out of power in Westminster too. In the 2011 Holyrood elections, Salmond led the SNP to a landslide victory.

Facebook Twitter Pinterest Salmond, receives applause for his address to the SNP conference in 2011 after the landslide election victory in the Scottish elections. Photograph: Jeff J Mitchell/Getty Images

Holyrood’s proportional voting system was designed to promote power-sharing. But for the first time since the Scottish parliament’s formation in 1997, Salmond was leading a majority government. That in turn put the SNP’s quest for a referendum on Scottish independence immediately on to the agenda.

The SNP was unprepared for this, but within a year the UK government headed then by David Cameron, a Tory prime minister, agreed to legally enable a referendum to take place. At that stage support for independence hovered at around 32%; by September 2014 when the referendum was held, the pro-independence vote had jumped as high as 52% after a remarkably vigorous and passionate campaign, putting the UK government into a tailspin of panic.

Facebook Twitter Pinterest Alex Salmond gives his last speech as SNP leader in 2014. Photograph: Murdo MacLeod/The Guardian

In the event, Salmond and the independence campaign lost 55% to 45%. Overshadowed during the campaign by his deputy, Nicola Sturgeon, Salmond resigned as first minister and SNP leader the following day.

Sturgeon was anointed party leader and then first minister in November 2014 without a contest. Buoyed by an extraordinary surge in SNP membership after the independence referendum, under her leadership the SNP won nearly every Westminster seat in Scotland in the 2015 general election.

Diminished by the defeat in 2014, Salmond became his party’s foreign affairs spokesman at Westminster – a role he never appeared to enjoy, often subtly contradicting Sturgeon in public on policy. Over the following years their once-close friendship came under strain and has since been destroyed.

After the 2016 Brexit referendum found Scotland voting in favour of EU membership while England voted to leave, Salmond helped persuade Sturgeon this was the time to launch a fresh campaign for Scottish independence. He believed this the best possible opportunity to do so.

Facebook Twitter Pinterest Salmond takes part in an EU debate with Boris Johnson, host Aasmah Mir and Labour’s Liz Kendall in June 2016. Photograph: Getty Images

Yet angry that Brexit was being weaponised to resurrect independence, Scottish voters disagreed; the SNP lost 21 of its 56 Westminster seats in the snap election called by Theresa May in 2017. Crucially, one of those was Salmond’s. He was furious. After 30 years in either the Commons or Scottish parliament, and at one time in both, he was out of power.

Facebook Twitter Pinterest Alex Salmond lost his Gordon seat to the Tories in June 2017. Photograph: Andrew Milligan/PA

Senior party sources say Salmond blamed Sturgeon’s election campaign. Nursing his wounds, he sought other employment and landed a controversial contract with the Russian government-funded TV station RT to host a chatshow. Sturgeon was furious about that, and made it clear privately.

When news of the Scottish government’s internal investigation leaked, Sturgeon chose to firmly side with her officials and the complainants, rather than her former mentor and close friend. In the days since winning his civil action against the Scottish government, Salmond’s grudge against her grew into an open feud, appearing to end any prospect of his return as an SNP figurehead.