Our starting point is 191 Brompton Rd in Knightsbridge 1. "I want the agency to be judged by the creative product," Frank Lowe declared on giving up the managing directorship of Collett Dickenson Pearce to launch his start-up, Lowe Howard-Spink, above a shop in Brompton Road in 1981. A quarter of a century on, Sir Frank's controversial and contradictory character continues to fascinate - and the Lowe group struggles to find a new role for itself in a changing communications world.
Next, the site of the 1972 launch of Cosmopolitan at Chestergate House 2, which changed the face of women's titles. It struck a chord with millions of women enjoying unprecedented financial and sexual freedom and spoke to them with a frankness and intimacy unknown in UK magazines at the time.
A stop for breakfast at The Ritz 3, the site of many history-making breakfasts over the years. Few will have been more significant than one in 1999, when Maurice Levy, the Publicis Groupe chairman, met his Saatchi & Saatchi group counterpart, Bob Seelert. It was this meeting that set off a chain of events that culminated in Levy's successful £1.24 billion bid for Saatchis the following year.
Just around the corner is St James Street 4, the first home of Media Buying Services. The origins of the UK's first media independent go back to 1970, when Paul Green, then Garland Compton's media manager, decided to go it alone. His innovation was not widely welcomed. "Phrases like 'flash-in-the-pan' abounded," Green later recalled. Guess who had the last laugh.
A brief stop at 101 St Martins Lane 5, the first home of Carlton TV, which many years later merged with Granada to create a £2.6 million giant.
Then down to Carmelite House 6, the first home of The Mail On Sunday, which first hit the doormats on 2 May 1982 with a splash about the RAF's bombing of Port Stanley in the Falklands. In the end, poor circulation meant it was the paper itself that nearly bombed. Its proprietor, Lord Rothermere, drafted in the Daily Mail's Sir David English, who, for three-and-a-half months, slept on a camp bed in his office until the paper got back on course, thanks in large part to the launch of its You supplement.
Years before, it was from Bouverie Street 7 that Rupert Murdoch's News Group first appeared, buying the News of the World in January 1969. But it was his takeover of the moribund Sun later that year and its relaunch as a tabloid that set the scene for battle. Nine years later, The Sun was outselling its biggest rival, The Mirror.
Time, then, for a few moments of quiet reflection in St Bride's Church 8 where, in June last year, a service was held to mark the departure of the last major news organisation from Fleet Street. Reuters' move to Canary Wharf completed a process begun nine years earlier when Rupert Murdoch's News Corporation took The Sun and the News of the World to Wapping.
British advertising reached a new milestone in Fetter Lane 9 on 14 November 1969, when, at a cost of just £23, Lintas booked the country's first colour commercial on TV. The 30-second spot for Birds Eye Peas went out at 10.05am during an episode of Thunderbirds.
Back to newspapers. In July 1984, the Mirror Group's Holborn Circus 10 headquarters fell under the control of the swaggering, arrogant and bullying Robert Maxwell. After Maxwell's mysterious drowning in 1991, the Mirror went through a protracted crisis before ending up in the hands of Trinity Mirror, its current owner.
WPP, as we now know it, was born at 64 Lincolns Inn Fields 11. In 1985, it existed as Wire & Plastic Products, a low-profile manufacturer of supermarket trolleys valued at just £1.4 million, which Martin Sorrell, a former Saatchi & Saatchi finance director, identified as an ideal shell company from which to launch a global marketing services operation. Within four years, the reincarnated WPP had acquired two Madison Avenue giants, JWT and Ogilvy & Mather.
71 Kingsway 12 was the home of Ray Morgan & Partners. In 1985, the eponymous Morgan led the media department exodus from the newly merged D'Arcy Masius Benton & Bowles, taking millions of pounds worth of business with him.
The move established the media independent as a permanent fixture and RMP went on to become a key component of Zenith.
Howell Henry Chaldecott Lury, the agency once lauded and derided as the enfante terrible of British advertising, was born at 94 Dean St 13 in a former brothel above a reggae music store. Its early life was symbolised by a creative product both irreverent and never easy to ignore. Brands such as Tango and the AA were re-energised as a result of it; others, such as Go and Egg, were launched on the back of it.
On to another iconic ad agency: Bartle Bogle Hegarty began life at National House, 60-66 Wardour St 14. "We were leaping into the dark," John Bartle later recalled. "We had no business, we'd vowed we wouldn't do creative pitches and our houses were on the line. A lot of people forget that."
6 Golden Square 15 was the important first home for those industry upstarts the Saatchi brothers. By moving in to one of the most elegant buildings in the area, Maurice and Charles signalled their intention to become serious players in adland. Years later, the brothers returned to the square with M&C Saatchi and, today, their neighbours include WCRS and the outdoor specialist Clear Channel.
A huge wave of publicity was generated by the online clothing retailer Boo.com when it launched from its 5-7 Carnaby Street 16 offices at the end of 1999. Within six months it had become the UK's first major victim of the dotcom collapse.
In these days of fragmented media, it is hard to imagine the impact of a TV show such as Sunday Night at the London Palladium 17. First screened on 25 September 1955, it played a crucial part in the establishment of commercial TV. Three days earlier, viewers had watched the first commercial to be shown on British TV - Young & Rubicam's spot for Gibbs SR toothpaste.
The film won its place in history by coming first in a lottery against 23 other advertisers competing for the honour.
A well-deserved stop for lunch at Le Gavroche 18, where Edward Booth-Clibborn's £448 lunch bill for two while D&AD chairman in 1991 was seen as spectacular even by adland standards. The bill, charged against "PR", included two-and-a-half bottles of wine, the half bottle costing £126.
It came to light during an investigation launched by D&AD's incoming president, Tim Delaney.
Booth-Clibborn later left with a £60,000 pay-off - to the fury of many D&AD members.
Appropriately enough, Campaign's first office at 5 Winsley Street 19 is now just a short walk away. The magazine launched with a coverprice of 2s 6d and quickly became a must-read. "No-one dared miss Campaign on a Thursday morning," Michael Jackson, its first editor, recalls. "They needed to know whether they were about to be fired, or lose an account."
Or even when they might become internationally famous. Ayer Barker's office at Metropolis House on Percy Street 20 was where Salman Rushdie produced Midnight's Children in 1981 while keeping his day job in the creative department.
Almost four decades on, it is difficult to appreciate the significance of Martin Boase, Gabe Massimi and Stanley Pollitt moving into Kings Court 21, off London's Charlotte Street, to launch their agency. BMP was the pioneer for the agency breakaways that followed it. Not only did it place great emphasis on its planning prowess, but also on the potency of its creative product, which made it the first serious rival to CDP.
Now to 33 Charlotte Street 22, the site of the launch of Channel 4, which, from the moment it went on air in November 1982, has played a major role in the liberalisation of British TV. Just as influential in its own way was the AAR, which came into being at 71 Chiltern St 23 in 1975 as the first, and still the most successful, agency matchmaker.
Broadcasting from a former gin factory in Oval Road, Camden 24, Classic FM was the UK's first commercial network devoted to classical music. Camden was also the venue for the launch of TV-am at Hawley Crescent, Camden Lock 25, the first UK commercial breakfast show.
On the way back into town we pass 110 Euston Road 26, an early home of CDP - the advertising manifestation of the Swinging Sixties. Charles Saatchi, David Puttnam, Alan Parker and Robin Wight all honed their talents at the agency. And it was there that the creative director, Colin Millward, successfully blended the charm of Bill Bernbach's work in the US with British humour. The result: a host of memorable campaigns from Heineken to Hovis.
Euston Road 27 is also home to Capital Radio, from where, on a morning in October 1973, Simon and Garfunkel's Bridge Over Troubled Water became the first song to be broadcast on a legal UK commercial radio station.
It came from the Euston Tower studios of Capital Radio, the second commercial broadcaster to go live in the UK (the first was the talk station LBC just a week previously).
Not far away, 14 Bruton Street 28, in the heart of London's Mayfair, was the appropriately stylish location for the first home of Abbott Mead Vickers, probably Britain's most successful agency and certainly one of its classiest.
Back to newspapers for the end of the tour, The Independent's appearance in 1986 from 40 City Road 29 made it the first new quality daily paper to appear in the UK for more than a century and provided a wake-up call to a newspaper industry that had been dismally slow to modernise.
Times Newspapers, meanwhile, was the first paper to take on the might of the print unions from its 200 Grays Inn Road HQ 30. In 1978, senior managers decided to close four titles rather than cave in to the National Graphical Association. What was supposed to be a "short, sharp shock" lasted almost a year. But, by the time the stand-off ended, union power was never to be the same again.
Where else to end but with dinner at The Ivy 31? If the walls of this famous eaterie could talk, what tales they would tell about hirings, firings, mergers and account switches. Long may it all continue.