That's partly because he is a relative newcomer to front line politics, having first been elected at the 2017 snap general election. He does not have a personal Twitter profile - making him one of just a handful of Scottish MPs not found on the social media giant.
But he has long been a familiar face to senior Tory members north of the Border, thanks to his spell as the party's vice-chairman in the William Hague era in the late 1990s.
Mr Jack unsuccessfully stood for election in 1997 in the Tweeddale, Ettrick and Lauderdale constituency, finishing third behind future Scottish secretary, Lib Dem Michael Moore.
Two decades later he won the Dumfries and Galloway seat from the SNP's Richard Arkless with a majority of 10.9 per cent.
While some newcomers to the Commons can take time finding their feet, this rookie MP was quickly identified by the Tory apparatus as a man of ability. He firstly acted as an aide to the Leader of the House of Lords - an important position given the Upper Chamber's hostility to certain items of Brexit legislation. He was soon promoted through the whips office to become Lord Commissioner of the Treasury.
In 2018, Jack was one of 62 Tory MPs to sign a letter calling on the UK to make a clean break with the EU. The letter said the UK must gain full "regulatory autonomy" after Brexit, and must not be stopped from negotiating trade deals with other countries.
Mr Jack is a successful businessman who has made millions building up and then selling self-storage firms. In a 2007 interview with The Scotsman, he was described as having "built a reputation as a ferociously clear business thinker".
Educated at Glenalmond, then at Heriot-Watt University, Jack always presumed that he would run his own business. He co-founded the tent-hire firm Field & Lawn in 1987, which doubled its turnover every year for a decade.
"The important thing to learn is to focus absolutely on what matters," he said. "In any business you can be led astray. In Field & Lawn as an example, people were always coming along and saying, 'You should be in the catering business' or 'you should employ a flower arranger'. Wrong."
The MP is also a farmer and landowner, running a large dairy farm near his home in Dumfries.
Mr Jack voted Leave but represents a constituency that voted 53% - 47% in favour of remaining in the European Union. In response to numerous queries from his constituents regarding his Brexit stance, the MP published an open letter explaining his position last year.
"I hope we will leave cleanly - I have never recognised the terms 'hard' or 'soft' Brexit - only that we should have control of our money, our borders, and be sovereign to make our own laws," he wrote.
"I want us to still have access to the Single Market on a tariff free basis - that is in both parties interests, not least because we spend €90 billion more with the other 27 members than they do with us."
The MP faced criticism from the SNP when he voted in favour of Theresa May's controversial Brexit deal in February - only to vote against amendments which could have made a no deal more difficult.
Emma Harper, an SNP MSP for the South Scotland region, told a local newspaper: “Instead of representing these businesses and the majority of his constituents, Mr Jack is giving in to the hard right of the Conservative Party and letting the likes of Jacob Rees-Mogg and Boris Johnson take us closer and closer to a no deal disaster."
In a statement released shortly after his appointment, Mr Jack said: “We need to continue to defend the Union against those who would seek to tear it apart. In 2014, the people of Scotland voted to remain part of a strong United Kingdom.
"We will stand up for their decision against those who would try to impose unwanted and divisive constitutional change."
Mr Jack faced criticism in 2017 when a Sunday newspaper revealed he owned over £70,000 of shares in a firm registered in a territory described as the world’s “worst” tax haven.
The MP had the investment in Jardine Matheson Holdings (JMH), which is incorporated in Bermuda.
An SNP spokesperson said: “Voters will have questions over whether these outside interests will influence Mr Jack’s positions – particularly when it comes to pursuing tax justice.”
There is no suggestion that the company has not paid taxes across the world.
A spokesman for the Scottish Conservatives said at the time that Mr Jack would not be disposing of the shares, adding: “Quite rightly, there is no law banning politicians – or anyone else – from becoming involved in companies which happen to be registered in Bermuda.”