Since he took over as managing director of STV in July 1990, he has single-mindedly pegged costs and maximised profits to guard against the looming prospect of a takeover bid.
While that was a remote danger under the old broadcasting rules, the game is changing rapidly. From the end of November, any one company was allowed to own two franchise territories for the first time, sparking the bids by Carlton for Central and Granada for LWT. From yesterday, non- media and companies from other European Union states can also buy ITV operators.
And this year, a joint committee of the departments of Trade and Industry and National Heritage is due to recommend yet more deregulation to be incorporated in a new Broadcasting Bill.
For a company of STV's size - valued on the stock market at pounds 218m, little more than a third as big as LWT, every liberalisation strips away another shield against predators.
But Scots do not come much cannier than Macdonald, whose career is a story of the long march from one side of Glasgow to the other, via London, Edinburgh and Manchester.
The journey has taken him from being a shipyard strike leader to the scourge of the television unions - a similar path to that of another 1960s left-wing torch, LWT's Greg Dyke.
Both became TV programme- makers who decided that their calling was being crippled by management-union conspiracies. Both rose to positions where they could clean the stables of corruption and overmanning, easing the blow with fat redundancy cheques.
Both became personally wealthy - although Dyke's pounds 7m comfortably outstrips Macdonald's million or so.
He has a large flat in Glasgow, designed by the Victorian architect Alexander 'Greek' Thomson, where he lives with his wife, Alice. They have two daughters, aged 26 and 28.
'The views people hold when they are young are often quite different from those they hold when they are mature and have gained experience,' he explains. 'I think I've just been constantly in touch with changing realities.'
An only child born in 1940, the son of a Clydeside docker, Macdonald trained as a shipyard fitter, led an apprentices' strike, joined the Govan and Gorbals Young Socialists and became chairman of the Clydeside Junior Workers' Committee - battle honours which were to be very helpful in the radical chic London media circles of the 1960s.
When the shipyards began to close in 1963, Macdonald went to London to seek work. His Labour Party contacts found him a job as circulation manager of Tribune, the left-wing magazine. He used that toehold in Fleet Street to persuade the editor of the Sunday Times, Harold Evans, to give him some work on the 'Insight' investigative team.
That enabled him to land a job as features writer on the Scotsman in Edinburgh, helping Magnus Magnusson (now of Mastermind) to launch an investigative unit.
Two years later, in 1967, Macdonald became the first editor of the Scotsman's new business section. That proved timely, for a couple of years later David Plowright at Granada Television was reviving World in Action and was looking for an experienced journalist with a financial background.
It marked the beginning of an 18-year stint that established Macdonald successively as a TV presenter and executive.
Apart from World in Action, he fronted Granada's party conference coverage for several years as well as prestigious programmes such as What the Papers Say and, inevitably, Union World. Returning regularly to London in this considerably more glamorous guise, he slipped easily into the Establishment milieu and became a member of the RAC and Reform clubs - as are several union leaders, he quickly points out.
Macdonald eventually forsook the greasepaint for management's greasy pole, ending up as head of current affairs. That was when he discovered that unions were not necessarily unalloyed good news.
'The life was squeezed out of TV companies by the labour movement,' he declares. 'It didn't serve the public to have 10 people on a current affairs crew; it was just a greedy monopoly.'
In 1986, he was lured back north of the border to be STV's director of programmes, succeeding four years later to his present job. There he acquired the nickname 'Ghost' Macdonald, because the staff never seemed to see him round the building - unlike his predecessor and present chairman, Bill Brown, who habitually lunched in the canteen.
Instead, he gained a reputation for slashing the payroll. More than half the staff was paid off as Macdonald cut the number of workers from 800 to 330.
Last month the heads of programmes, entertainment and documentaries, and the sports editor, were either given their cards or had their jobs merged.
'In fact, we are employing more people than ever before,' Macdonald insists.
'Before, there were 800 staff making 500 hours of programmes a year. Now we make 1,000 hours a year with a core of 350 and another 250 on contract. Because we have developed quite a big business in network production, we have a thriving freelance side. Airtime sales and other services like cleaning have been contracted out, and even our engineers have formed their own company.'
However, that still means that STV saves on holidays, pensions and national insurance and, as Macdonald admits, this gives the company the flexibility to step these services up or down as circumstances require.
One redundant former executive said: 'He has a very large ego, and he's very determined. But I'd rather you didn't mention my name, as I still want to work in this industry.'
While the group's profits marked time in the first two years of Macdonald's reign, they showed signs of breaking out in the first half of 1993 with a jump from pounds 2.2m to pounds 3.1m.
STV's production for the rest of the ITV network has been hived off into a separate company, Scottish Television Enterprises, which is already one of the largest suppliers of children's programmes in Europe and aims to become a force on the European scene.
It also has a 20 per cent stake in Good Morning Television, which should gain from the revival in advertising as the economic recovery gathers pace.
A month ago, Macdonald claimed confidently: 'I am peering over Hadrian's Wall, waiting for an opportunity to invade.'
But now he is gazing more warily into the new year, saying: 'We have just been keeping a close watch on the situation. We'll have to see how the dust settles.'
Sadly for Macdonald's defence strategy, STV shares have defied the stock market surge, falling by about pounds 1 as the year ended, from their 1993 high of 553p.
Some observers have speculated that a hostile bid for STV could be the excuse the tartan army needs to dust down its claymores for the first major battle against foreign invaders since Guinness snatched Distillers so controversially more than seven years ago.
STV's board bristles with the so-called Scottish mafia, from Sir Charles Fraser and merchant banker Angus Grossart to Gavin Laird, general secretary of the Amalgamated Engineering and Electrical Union, Macdonald's old union.
But while Macdonald is more than happy to play the Scottish card, he wisely does not rely on it.
'Any bidder would have to conform with our licensing agreement, in which commitment to Scotland is very important,' he points out. 'The nationality of the ownership is irrelevant, so long as the commitment is there.
'But we in Scotland have suffered a lot from the 'branch factory' economy. We'd fight to retain control in Scotland.'
Macdonald now forswears any party political allegiance, having voted for all main parties at different times.
But as he toasted 1994 in his flat in the small hours of yesterday morning, Macdonald faced a potent reminder of his early fights - his mother, Jean, who may veer nowadays between support for Labour and the Scottish National Party but still delights in drawing her son into argument.
'I was brought up in a political household, and I still pay my dues to Amnesty,' Macdonald admits. 'But statism is not a viable option any more.'
Bobby Campbell, features editor of the Scotsman and a friend of Macdonald for over 30 years, said: 'He's had a bumpy ride from Clydeside to the management floor. In the course of that he's lost a few friends, but he has basically remained the same guy. People on the left are always looking for hero figures to produce a socialist paradigm. I have always thought that was extremely naive.'