It was during Saturdays and holidays spent working in the grocery store that Mr Gardiner developed a liking for business.
This led him to embark on a business studies degree at Edinburgh University after leaving Lockerbie Academy, and then a career in accountancy.
The grocery store is no more, with Lockerbie having experienced the same shift in spending patterns as other market towns towards supermarkets.
However, the basic importance of customer service, which became evident to Mr Gardiner in his formative years, has stayed with him.
Edinburgh-based Mr Gardiner, who took over as the Scottish head of PricewaterhouseCoopers (PwC) this summer when Frank Blin handed over the baton to take on a portfolio of part-time roles, said: "My folks had a grocer's shop in Lockerbie all the years I was growing up.
"My point about customer service – that is something ingrained in me when I was much younger. You provide good service and you get some customers."
Days spent in the Lockerbie grocery store, he revealed, were also crucial to his eventual career choice.
Mr Gardiner, who is 47 and headed PwC's Scottish audit and assurance practice for two years before taking on his current role, said: "Why did I become an accountant in the first place?
"Having been involved in a family business, I just liked business, so that is a natural progress. I did business studies at university, then did accountancy."
After qualifying as an accountant with a small firm in Edinburgh, Mr Gardiner moved into the big firm arena in 1989 by joining Deloitte Haskins & Sells, which merged in the UK with Coopers & Lybrand, before the enlarged entity combined with Price Waterhouse to form what is now PwC.
Mr Gardiner said he joined Deloitte Haskins & Sells with a view to staying for a couple of years, but added: "Two years is now 23."
And those years have been eventful. Mr Gardiner was lead partner on the audit of Northern Rock when the bank was hammered by the seizing up of wholesale funding markets in 2007.
He said: "People talk a lot with the benefit of hindsight. If you go back and look at the financial statements, Northern Rock's business model wasn't a secret.
"It was clear what they were doing. It became a liquidity crunch issue.
"There was a very clear point when wholesale markets just closed, in August 2007 and the run on the bank was (September) 2007. There was a clear event that happened.
"Maybe with the benefit of hindsight, they would have done things differently."
However, he is adamant the auditors did what was required of them, in terms of ensuring everything was clear in the accounts.
He said: "It was a fascinating period, in terms of getting involved with the Government and Treasury, and helping Northern Rock look at potential solutions prior to the nationalisation.
"We had a team of about 30 working with Northern Rock in the period up to it being taken into public ownership."
Asked for his view of the public's perception of the audit profession, he pointed to a bit of a mistrust of groups including politicians, because of the expenses scandal, and bankers, given the state of the economy.
Mr Gardiner added: "I can understand why commentators and the public might say, 'Where were the auditors?'"
However, he is robust in his defence of the audit profession, declaring that it had done what it was required to do in terms of scrutinising, and reporting on, financial statements. Mr Gardiner said: "I think a lot of lessons have been learned, but did the auditors have a bad credit crunch? No.
"We perennially have to deal with an expectation gap in terms of what is our role."
Mr Blin maintained a high profile during his years in charge of PwC in Scotland.
Asked if Mr Blin was a hard act to follow, Mr Gardiner said he was "clearly hugely pleased to have taken over from Frank Blin" and that his predecessor was a "tough act to follow".
He added: "PwC in Scotland was very closely associated with Frank and vice-versa. He was great for us in the business community.
"One of the things I am very keen to push is that we have a very broad team and a real depth of specialism. We have 35 partners in Scotland, so I am very keen [on] more profile for more people, so the market really does understand the depth and breadth of the team."
Referring to PwC's workforce of about 900 in Scotland, he said: "PwC is about more than Lindsay Gardiner. It is about the people we have here."
In terms of his plans for PwC, Mr Gardiner spoke of "evolution not revolution". He highlighted the fact the firm was in growth mode in Scotland, and the particular buoyancy of the Aberdeen market. His first assignment last Monday, he noted, was to address 70 university graduates joining the firm in Scotland.
Mr Gardiner also highlighted a focus on the energy sector, in terms of oil and gas, renewables, and utilities. He cited financial services, given its importance to the Scottish economy, noting financial services was not just key to Edinburgh but also "growing in importance" to Glasgow.
He also flagged a focus on government work. "Government is a big part of what we do," he said. "We have a devolved government, a devolved executive."
While seemingly at pains to avoid becoming embroiled in constitutional arguments, beyond declaring there was a need for "hard facts" to inform the independence debate, Mr Gardiner said: "There will be some sort of constitutional change over the next three to four years, depending where you end up on a spectrum between status quo and full independence. Something will change."
He added firms would consequently need help with tax issues, and PwC would "need to be clear how it affects our business as well".
Mr Gardiner highlighted his desire to raise the amount of work which PwC did for private businesses in Scotland, citing a "misconception" the firm was interested only in bigger publicly-quoted companies and multinationals. "We are not necessarily more expensive than some of the smaller firms," he said.
He meanwhile cited a focus on "making sure that we deliver the best possible customer service".
"It is a competitive market," he added. "We don't have a divine right to deliver services."
Mr Gardiner, who is married with daughters aged six and eight, enjoys golfing, walking and gardening. He also supports Queen of the South football club, currently top of the Scottish Second Division after being relegated last season.
"The first score I look for on Saturday is Queen of the South. I don't go as much as when I was younger but I still try to get to two or three games a year."
Mr Gardiner indicated a willingness to take on external appointments, but said he did not have the time to take up a non-executive directorship of a company. On preferences, Mr Gardiner quipped: "Definitely not Queen of the South," but said he would be happy to take on a children's charity role.