So when it happened three weeks ago few people took much notice. The next day's Mail was being re-made in its usual way, it seemed. In fact, standing in the middle of the newsroom for all to see, Dacre was ripping up a dummy issue of Metro, Associated Newspapers' first newspaper launch for 17 years.
The destruction of the dummy effectively marked the end for Kim Chapman, formerly editor of the Reading Post, who arrived to edit Metro only last November. She was replaced as editor and offered the post of Metro's publisher, which she turned down, and then Dacre brought in some of his most trusted lieutenants from the Daily Mail to turn the paper around in time for its launch on 9 March. Alistair Sinclair, Dacre's deputy on the Mail, was given overall control of the project and Ian MacGregor, associate editor (news) and a rising star at the Mail, replaced Chapman as editor. Other executives drafted in from the Mail include Tim Jotischky, the paper's executive news editor.
What Chapman had failed to understand is that Metro is very much more than just a free regional newspaper for London.
Associated has highly successful newspapers, but it is still dependent on just three national titles. The cash generated by the Daily Mail, The Mail on Sunday and Evening Standard has not been used for company expansion, except for a few excursions into cable and new media. With the launch of Metro, Associated hopes to create a blueprint for a series of local free newspapers for Manchester, Newcastle and, perhaps, even New York.
It also gives it another way to tackle what Associated calls "the problem in London". Despite massive investment in new sections and price-cutting, sales of the Evening Standard are stubbornly stagnant. Associated needs Metro to protect its position in London from rivals who may be tempted by the same freesheet idea.
The idea is not original. According to legend, the new Lord Rothermere, then known as humble Jonathan Harmsworth and deputy managing director of the Evening Standard, was in Stockholm on a bitterly cold day when he couldn't get a taxi, so he jumped on to a tram. There he saw all the other passengers reading a newspaper that came free from a display bin on the tram.
The paper was produced by Sweden's Modern Times Group, so Associated head-hunted one of its directors, Thomas Grahl, to bring the idea to London. Modern Times was planning its own launch in London but, crucially, Associated Newspapers got to London Underground first. It signed an exclusive 10- year contract that promises the Underground about pounds 1.5m a year if the paper is a success. It also gets a page a day in the newspaper to promote its services and apologise for signal failures on the Northern Line.
In return, Associated gets to place 1,000 newspaper bins in 261 stations on the Underground. It has bought access to many of the 2.7 million passenger journeys made every day on the Tube. Most of the people making those journeys are relatively upmarket and young - people who will be attractive to the advertisers Associated hopes will spend pounds 13m a year on ads in Metro. As it tours advertising agencies, Metro's sales team is offering to refund advertisers' money if it does not hit a 90 per cent pick-up rate for its 350,000 print run.
The paper hopes to cash in not only on the arts and entertainment classified advertising that drives the Standard, but also on the relative dearth of colour display advertising sites in newspapers. Recent increases in production quality have driven many advertisers to demand colour pages in newspapers for their ads. Media buyers despair at the lack of availability of colour pages to run their campaigns, so the all-colour Metro hopes to mop up some of this demand.
The media buyers who have seen the new dummies of Metro believe its quality means thatn it will destroy the Evening Standard. Yet Associated seems to have been forced to do it because it was terrified someone else would sign up the Underground.
In the world of fragmenting media, mass audiences are becoming increasingly valuable, wherever they may be. TDI Inc, the American poster business that bought London Transport Advertising when it was privatised, has built an entire European business on the money that pours in from advertisers keen to hit the Underground's audience.
As car congestion gets worse and the Government's car taxation policies and investment in public transport get under way, the Underground can only become more attractive. The number of journeys on the Underground have increased by nearly 70 per cent since the early Eighties, and Associated has gambled that someone was eventually going to go for that audience.
What was wrong with Chapman's dummy Metro was that it looked like a regional newspaper - hardly surprising, given that it is to be a regional newspaper, and was staffed and edited by regional newspaper journalists. The Mail troubleshooters found 22 relatively inexperienced reporters, working in very different conditions from those at Associated's West London HQ.
Metro has been deliberately sited in East London's Docklands, to avoid its being infected by the rest of Associated's culture of editorial largesse. Where the Mail's Saturday Weekend section alone costs pounds 13m a year, Metro's budget is less than pounds 10m a year for a five-day operation.
The Mail's newsmen have quickly to turn Metro into what Dacre wants - a 40-page print version of GMTV, celebrity-heavy, middle-market and glamorous. It will be stapled to make it easy to read on the Tube, and its bite-sized stories should mean you can read all you want of it on a 20-minute journey.
The other important thing about Metro is that it is Lord Rothermere's first project. It has been his baby since the beginning, and is his opportunity to prove that he can step into his father's shoes. For Paul Dacre, Metro is important for reasons beyond its size and cost.
Dacre wants to prove that his partnership with this Lord Rothermere can be as successful as Sir David English's partnership with the previous one. And then there is the question of the Evening Standard.
Ironically, London already had a "Metro" newspaper and it was published by Associated. For "Metro" was the name that appeared in the top right- hand corner of the first edition of the Evening Standard - an edition that was on the streets at 9am. It has now been renamed "News Extra". But still the Standard is worried. There is no question that Associated might want deliberately to damage its London paper, but given the frosty attitude that reportedly exists between Dacre and Max Hastings, the Standard's editor, there is probably at least some internal politics in Dacre's enthusiasm for the project.
The mighty house of Harmsworth is not going to live or die by the success of an pounds 8m investment in a free newspaper for the Tube, but dynasties are at their shakiest after a succession. Dacre and his favourite sons from the Daily Mail back bench have a reputation for excellence. Now they have to prove it once again, so that the new Lord Rothermere can show that the dynasty is safe in his hands.