As the Chancellor's emergency Budget looms, the man who for the past five years has been the loudest voice of UK business is talking all about the small and midsized firms that matter so much to Scotland.

John Cridland, who steps down as director general of the Confederation of British Industry later this year, says the chancellor should be focused on removing red tape, boosting investment and exports, and encouraging training, in that vital core of the business population.

"I am on a mission to build a Scottish 'mittelstand'," Mr Cridland said in Edinburgh last week, conjuring the vision of a German-style stratum of vibrant midsized corporates. "We can do that just as easily here, Scottish business is flying, and the real engine of growth is in the middle. Large companies are important but the forgotten army is the medium-sized businesses."

He says Scotland has to move from "thinking start-up to thinking scale-up".

The CBI is calling for a package including permanent status for the £500,000 annual investment allowance, and a boost for venture capital trusts and the private placement market. "What those companies need is patient capital," Mr Cridland says, adding that his membership is "predominantly small and medium companies" - while adding: "I hope I have abolished from the Oxford English Dictionary the dreadful term SME".

At a time of scrutiny of its largest member companies, especially any who might minimise their UK tax bill, Mr Cridland wants to get onto the front foot with a 'great business debate'. He explains: "Business has not made it clear enough that we are the consumer champion, we have left it to others to speak up for the consumer.....we need to take back things that are properly ours, business is a force for good because it does good every day in the way it delivers excellent service for consumers."

But he admits: "There are other issues where we are on the back foot where people are raising leigitimate challenges. Does business pay its fair share of tax? I am not sure the public knows that one third of all the taxes raised come from business."

The CBI chief says the most important issue for Scotland is for government to give an immediate green light to this week's Davies Commission recommendation for a third runway at Heathrow. "I think the Scottish (CBI) council has been very clear that Scottish business and our ability to export can benefit from business men and women being able to fly more easily to the hub airport."

The lobby group's other key wish-list issues are more support for research and development, housing, and other infrastructure. So on the derailing of Network Rail and the threat to the government's pledge to develop infrastructure away from London, Mr Cridland admits to "a lot of disappointment". He says: "You have got to have effective delivery, occasionally there is a time when you have to press the pause button, but the business community is absolutely determined that these investments continue."

Mr Cridland is steeped in lobby politics, having joined the CBI in 1982 and held most positions in the organisation, becoming the first insider to be appointed to the top job in 2010. He has said he feels he has "one more role" in him, and perhaps it might be in the area of skills and education. He was Vice Chair of the National Learning and Skills Council between 2007-2010, and is now a board member of Business in the Community and a UK Commissioner for Employment and Skills.

This year Mr Cridland was improbably trending onTwitter after calling for English GCSE exams to be scrapped.

The CBI's skills agenda is closely in tune with the recommendations of last year's Wood review for the Scottish Government. Mr Cridland says: "I have challenged both our own shareholders and the government on education policy.....businesses are making a big mistake if they only focus on secondary schools. He wants businesses to widen their focus to primary as well as secondary schools."

He goes on: "It is no good complaining about a lack of computer graduates if you are not getting seven-year-old girls excited about the coding skills needed to design a fashion website. Let's have a school system that works for all young people, at the moment the system fails too many who fall through the cracks - we have made very strong arguments about careers education, it is poor, it is too little, too late. You have got to help young people understand the implications of the choices about subjects - if they drop science or languages, what that means for their later lives."

Also centre stage in the CBI's great debate is the continuing damage caused by late payment - so why isn't the voluntary code working? "I think it's because business models are under real pressure because of the internet and digitalisation," Mr Cridland says.

But he is bullish about the UK's economic prospects. Despite the evidence of an apparently sluggish start to the year, Mr Cridland was insistent that the second quarter's figures would correct that - and he was proved right this week. "All of our surveys show a continuing positive trend," he said.

In fact, the CBI has been calling on its members to give workers a fairer share, with pay rises. "It's beginning to happen and it's the right thing to do," the bosses' leader says. "But pay rises are based on productivity growth, not government ministers telling companies they should."

The CBI leader believes the 'yes' campaign in the EU referendum has work to do, particularly in light of the travails of the Greeks. "I don't think we have managed to communicate the benefits very effectively, I also think we need European reform," he says.

He told the CBI's Scottish members: "We want to see the EU doing more of what it does well - like updating the single market and signing free trade agreements with the rest of the world - and less of what it does badly - including regulation on lifestyle issues or some aspects of employment law."

On the immigration debate, Mr Cridland says free movement of labour is critical to productivity. "Businesses needs to speak up for the economic benefits of migration - in Scotland they would not be as successful if they were unable to source Polish engineers."

The voice of industry says he has had "phenomenal levels of support for what I have said" - on the subject of exams and work experience. Beyond that possible legacy, he hopes his leadership has "reached out to all sections of society to explain what wealth creation is all about".