His senior position at Lloyds Banking Group did not stop colleagues giving Mr Grant some good natured ribbing when he built a Caterham track car from scratch in his garage a few years ago.
"People were saying to me you can go into a showroom to get a car, you don't need to get it in a box in bits."
Having joined Bank of Scotland straight from school as a 17-year-old he began learning the nuts and bolts of his trade in the branch network in Paisley.
He said: "The first day my mum sent me off into the world of work I suddenly realised that part of the challenge on day one, and banking at that time, was to get home before four o'clock because the branch closed at three.
"So much to my mother's surprise I was back home in Bridge of Weir by ten to four."
Three decades later Mr Grant is chairman of the Lloyds Scottish executive committee, effectively the group's top operator in Scotland, yet he jokes of being trained in Gilmour Street banking rather than the Wall Street equivalent.
Mr Grant said: "The role is partly to represent the group in Scotland but also represent Scotland in the group and be a bit of an advocate for the capability we have got here.
"For us Scotland is relatively distinctive, we are heavily weighted in resource with about 20 per cent when demographically it should probably be about half that.
"We have moved away from just trying to define the group through pounds, shillings and pence, towards actually, what the purpose of a bank is in the broadest sense and make sure that is brought to life in Scotland."
All self-deprecating aside Mr Grant is a key player in the upper echelons of Lloyds and appears to be among a select few former HBOS staff trusted by chief executive Antonio Horta-Osorio.
With his career covering corporate finance and risk as well as retail and private banking Mr Grant has a broad spectrum of experience to call upon. In more recent years, along with his Scottish duties, he has been overseeing the exit of Lloyds from a number of overseas markets with the countries it operates in trimmed from 30 to eight.
It all appears a long way from the youngster who used to spend an hour interviewing people before deciding whether they could get a £100 overdraft.
However, Mr Grant is adamant the "good grounding" he received is still relevant, even though the world has moved on.
He said: "I learned all through that time a lot of basics about people judgement, sometimes the hard way, and you also learn that most things, particularly in business and banking, are variations on a theme around confidence in people and your judgement and understanding of that."
Mr Grant's apparently practical nature comes through as he repeatedly talks about doing or providing "real stuff" or "real things" for customers.
He said: "This bank will only grow going forward as a function of the growth of the economy it is supporting and providing better products for its customers. Anything that is delivering value beyond these two things is probably not sustainable and should be challenged."
Similarly he acknowledges the need for industry leaders who have come through the financial crisis to embed the lessons learned into new generations to make sure mistakes are not repeated.
He said: "Banking went through a phase where the financial engineers were to the fore, the performance management side was to the fore and the strategy consultants were to the fore.
"Actually the whole cultural change [meant] that [banking] became very detached from the real world of customers. That is rebalancing right now and there is a need for people who understand a bank is all about customers.
"The reason that there is a bank is people wake up every morning and need things like save or borrow, basic things but without that there is no reason to have an organisation."
Mr Grant has also been taking a leading role in the working party set up by Lloyds to examine the potential outcomes of a Yes vote in the Scottish independence referendum.
He highlights the difficulties as there is no set position as to what would happen to financial services.
He said: "You would be horrified if you thought we weren't planning.
"It is looking at what the range of scenarios might be as presented by the various people informed in the debate.
"We have been heavily engaged with the UK government, our regulators and the Scottish government, primarily to help them understand the complexity of our business."
Unsurprisingly the issue of currency is a key one for the bank with Mr Grant admitting systems would need significant changes to accommodate something other than the pound.
However, he is adamant customers should not be fearful and said: "We are committed to Scotland and if it is the will of the Scottish people that there be an independent Scotland then this bank will do what it needs to do to accommodate that and service its customers in Scotland.
"That is what we are planning for.
"The planning is about how you would continue to sustain and support rather than what you wouldn't do."
Part of his remit in recent years has also been to oversee the Bank of Scotland brand and which he openly admits he takes great pride in.
He said: "Part of the strategy coming through is we now have clear ownership here for BoS retail in Scotland. Robin Bulloch on retail, Alasdair Gardner on the commercial side and Donald Gateley on the wealth side, the three of them running Bank of Scotland from the Mound and very distinctively co-operating together.
"There is a cadre of us who want to maintain the identity of Bank of Scotland.
"It is valuable and me and my colleagues are trying to bridge that and not lose it.
"That has been a big focus of me trying to get back almost to that bank, not where we interview you for an hour, but where there is a collective effort to deliver for our customers distinctively in Scotland."
Regaining some of the pride he felt as a teenager on securing a place with Bank of Scotland is among the reasons Mr Grant continues to strive for better standards in the industry.
He said: "I'm hoping over time people will think they want a career in banking."