WHEN he won election back to Holyrood last year Green MSP Mark Ruskell admits to a feeling of serendipity about being given the same Scottish Parliament office he had occupied before losing his seat almost a decade before.

"I treat each every day in the parliament as my last," says Ruskell, who insists his nine-year hiatus from Holyrood has made him acutely aware he may not have forever to use his platform as an MSP for the Green cause.

It's the sense of political mortality that could explain Ruskell sitting in his office in a near-deserted corridor on the ground floor of Holyrood's MSP's block on a sunny late-August afternoon during the parliamentary recess.

"We're in very changeable political circumstances and for me it's about pushing as hard as I can on the Green agenda", says Ruskell, who is busy drawing up his campaign plan for when MSPs return from their summer holidays next week.

"There are some real choices coming out in the next few months and we're going to be taking a hard line with the government," he says of the Green's six MSPs' plans to call out the minority SNP administration on key issues.

As his party's spokesperson on climate, energy, environment, food and farming – a brief that covers areas such as fracking and climate change – Ruskell may be wise to work on a bit of pre-season planning ahead of the parliamentary kick-off.

The Scottish Parliament includes a handful of "retreads", MSPs who lost their seats but managed to win election back to the parliament at subsequent elections, including Labour's Pauline McNeill, SNP Brexit minister Mike Russell and LibDem Mike Rumbles.

Like all of the above Ruskell had to find an another calling during his exile, which in his case involved work in the renewables sector and as an environmental lobbyist, as well as five years as a councillor in Stirling.

"It's really exciting to be back after nine years, but I also spent five years of that time in local government and that really informed my thinking in terms of the impact of austerity," he says.

"So it's a wonderful opportunity to effectively have had three political carriers," the Mid Scotland and Fife adds.

It was his time as a councillor, a post he held until this May – a year after his election as an MSP – that he says influenced his party's support for the minority SNP government's budget as part of a deal for £220 million of extra spending, including £160m for local authorities.

"I knew that a lot of pain was going to come unless we secured that," Ruskell says.

Scottish Labour leader Kezia Dugdale accused the Greens of backing "nationalism first, austerity second" by agreeing to support the SNP's spending plans. However, Ruskell insists it was a "good deal" and says "I spoke to people who had their job saved because of that".

But holding such sway over ministers is a far cry from the situation he faced when he last served as an MSP from 2003 to 2007 – the second term of the devolution era.

Ruskell was one of seven Green MSPs during that parliament, but he says the ruling Labour-LibDem administration of the day stymied his party's influence.

"I actually found session two quite frustrating because Labour and the Liberal Democrats had a majority and it was very hard to get things voted through," he says. "Now obviously with the Government in minority there's a great opportunity for a strong Green group to be pushing new ideas onto the table."

This time around, he says, the Greens have a chance to push the SNP to adopt radical positions such as permanently ruling out fracking – something he says will be a "key test" of Nicola Sturgeon's mettle.

"I'm optimistic that they'll make the right decision," he says about Government's final decision – due at the end of 2017 – on the controversial shale gas extraction practice, fracking.

But he also insists there is also an "urgency for them to make the right choice" in other key policy areas, as he highlights his plan for a lower the default speed limit in urban areas from 30 to 20mph, a campaign backed by the Sunday Herald.

"I see a lack of imagination within their programme," is his judgment of the SNP after a decade in power. "But there's an opportunity now for them to step up and realise that Scotland can be a leader on safety issues like this."

Plans like this are part of an agenda, he says, gaining widespread "public acceptance" in the way the smoking ban in pubs did over a decade ago.

He adds: "It feels like there's a tipping point here, one of those issues where everyone wants to see safer communities."

The 45-year-old MSP also insists that his party will continue to promote independence as a "more socially just" vision of society.

However, he says there are immediate "gaping holes that need to be filled" in areas such as the promotion of renewable energy and tackling climate change.

It's here that Ruskell talks about his influences, including the wartime Labour Scottish Secretary of State Tom Johnston – who Churchill described as "the King of Scotland" – who introduced a hydro-electricity scheme in the Highlands in the 1940s, when many rural areas outside the Central Belt had little or no supply.

Ruskell, who moved from the New Forest to Scotland with his parents at the age of 12, says his interest in Green politics dates back to a family holiday in Orkney in the 1980s.

"I can remember going up with my folks," he says "when I was 13 and seeing some of the wind turbines being tested and thinking wow this is the future by generating energy from wind."

But for now he says he is "making the best of every day" as an MSP in the remaining three-and-half years of the current Parliament to make those dreams a reality.