A brief warning: this article will feature the phrases "international matrix", "collaborative working" and "integrated structures".
I will try not to turn it into a management textbook, but will instead attempt to convey the complexity of meshing local and international market requirements in a way that is understandable - even so soon after the New Year celebrations.
It will delve into the "ambiguity" of profit and loss accounts across different business units and explain the many ways in which international and local teams are becoming closer and closer.
Frances O'Neil, managing director at MEC Global Solutions, explains that the aim of her department is "to grow the business for all, not just for ourselves. We have the whole network and the clients' business as our goal".
First, the good news: the days of "command and control" international account management are over. Template campaigns sent by PowerPoint have had their day.
It is also now very rare that a local market will get a surprise call from international, telling it that it has just picked up or lost account X or Y.
Good news if you have won it, but bad news if you have lost it thanks to the machinations or relationships in head office.
"It does still happen in certain markets, where relationships are still kind of old-fashioned and people have a patron and decisions are made in a smoke-filled room - if that's still allowed," says one agency boss.
Larger offices are now almost always involved in pitches and, depending on the brand, the UK usually qualifies on this score.
Colin Gottlieb, chief executive of Omnicom Media Group for EMEA, says: "Plot all the dimensions of our business on a chart, such as the talent expense, the pitch process and level of auditing, and put in every dimension, including digital growth and search, and you really would struggle to find another market in the world as competitive and challenging as the UK."
Another benefit is that big global brands can also help spread excellence and new thinking across a network - a role not always recognised.
Sue Byrne, head of international client service for EMEA at Universal McCann, points out: "Sometimes you are getting some of the brightest brains in the world, which is a significant advantage."
In essence, it's a move from the international coordination role - a mysterious process involving experts with spreadsheets, demanding more and more information, but never explaining what they do with it - through to collaborative working in which campaigns are built from the ground up.
Brands may still work to a global template, but it will be more nuanced and culturally sensitive and channel selection can be varied by market depending on the local media mix. The buzzwords for such integrated structures are joint ownership, mutual respect and engagement.
As Ailsa Lochrie, marketing director at MindShare Worldwide, puts it: "A great idea can come from anywhere. The central team has to spot that those ideas - that might have come out of Milan - could actually work across several markets and do that in good time, so you can make it happen. I see a lot of respect from the guys in the global positions for what local markets are producing."
MEC's O'Neil adds: "Someone executing a strategy in a local market has to feel it's rooted in local culture; local teams will want to feel they own that strategy and helped create it.
Universal's Byrne maintains: "Some clients are still 'take and translate', but for clients who need consumer engagement, it's much more 'local upwards'."
It's worth remembering that although local staff may sit in the same office as the international team, meaning meetings can usually be held face to face, the UK is just one of many offices that international has to deal with - it's just one more market.
"The UK is very much its own market. We have the same relationship with France, Germany and Japan," points out Lochrie.
Clearly, international has come a long way since the murky beginnings of media. Gottlieb recalls: "When I started out at CIA, our international office was a room that had a very nice lady in it and flags around the window ledge. It was kind of quaint."
The rise of multi-market pitches, media fragmentation and the need for expensive and ever smarter tools, have all played their part in the process. Current changes include clarification of the split between local and international.
Ian Manning, international business director at ZenithOptimedia, says: "There is much clearer delineation between the role of central and local strategy."
Central teams, he says, will increasingly look to the longer term, while local managers focus on the here and now. "Central teams are starting to be less about media planning," he claims.
Key to the international side of this role is sourcing information from the teams, but, Manning adds, they must be clear about why they need it to avoid reporting for its own sake.
Such clarification and structuring of the role of the international and local teams will also bring benefits to the business. "It provides a clearer role for what the centre brings to the business. Clients will recognise that and pay for that service," he says.
Over at Starcom MediaVest Group, part of the solution to the conundrum of local and global has been the appointment of client managing directors for key EMEA clients.
EMEA chief executive Iain Jacob says: "We are changing from being the international department, to having our organisation organised around international clients and their needs. That's very different from having a department that works with the client's international department."
He says that this reflects a switch in clients moving from country-by-country structures to a category-based structure, as in the case of his client, Kraft.
"Client organisations are getting pretty clever at managing that level of international matrix. Agencies are getting pretty good at it as well," Jacobs adds.
Starcom's new structure benefits not just the network, but also the local offices. "If it's working well, it means the local assignment is protected because we are also engaged with the company at an international level and there will be a lot of value-added going backwards and forwards," he says. "Local markets should be stimulated into feeding their best work into the international managing director."
Ultimately, he maintains, the dividing line between international and local will become harder to define.
"I want the group to be the most networked network, so that when a client in the UK is launching a new coffee brand, my domestic UK planner says 'we know how to launch coffee brands because we've done it 25 times in 10 markets'," he says. "The split between domestic and international assignments becomes less relevant."
Omnicom's Gottlieb argues that there will also be further change in terms of the services clients want, as well as the pitching process.
Once clients stop looking for financial savings and start asking "where should I spend the money", reviews based on spend efficiency - the current auditor model - become much less viable, he believes.
"It's a focus on return - the auditors won't know how to handle it," he says of a world where media success is based on top and bottom line growth. The solution in three to five years' time will be media rosters that can be trusted with "pretty sensitive" information and will compete on a project basis.
So, do all these changes mean the relationship between the UK office and the international team is now eternally cordial? The answer is no, because there will always be a natural tension between the demands of the network and the needs of the local office.
Take the case of one big global client. An agency network retained the business in one major market, but lost it in several others. A newsletter to staff trumpeted the win but ignored the losses, upsetting many of those who had worked hard on the account.
Then there's the fact that some international offices claim that the big markets - not just the UK - can be very uncooperative. London, they say, must not become too arrogant, because good work comes from everywhere and international accounts can be housed in whichever city hosts the client's head office.
Ian Rotherham, head of international at MPG, says: "There will always be an element of tension between central and local across all industries; likewise on the advertiser side."
Universal's Byrne adds: "It's a far stronger relationship - there's not always enjoyment, but there's engagement."
On the plus side however, as more and more clients go multi-market, the benefits of international have become clearer: one day the UK will need something from the network.
"We've seen more and more multi-market pitches and business moved on a global basis. This has meant local offices have realised that function is a large part of the armoury for acquiring new business," says Rotherham. "Large indigenous advertisers are few and far between."
One cause of natural tension is fees. Many multinational brands exploit their scale to pay less than a domestic client would. Rumours of accounts picked up at cost or even a loss abound - something that can impact on local economics.
"If it's pure planning and buying, terms are going to be less than most assignments because you are not buying digital, content or econometrics (as a domestic client might)," admits Jacob, who adds that some domestic clients pay very low rates indeed.
"Sometimes international clients want to do content development or search, but only in 10 or 20 markets."
Similarly, there is the oft-cited complaint that offices have to drop profitable local clients in favour of international goals.
Jacob, whose group has just dropped LG after picking up Samsung, points out that strong local clients can put a hold on network ambitions.
"An international client will come to you and say 'do you want to pitch for the business?' and you say 'no', because you have too many of these blocks," he says.
OMD has responded to such challenges by integrating the accounts of its international operations with its local teams in order to avoid tensions created by separate revenue streams, each of which could benefit if the other suffers.
"A lot of my competitors have separate international teams with separate P&Ls; I refuse to do that," says Gottlieb. "I want my French international team to be looking not at London as its boss, but the team in Paris."
So, what's the perfect mix for an agency? How much business should come from UK clients and how much from international?
Jacob suggests a 60:40 split is "a healthy balance", while MPG's Rotherham says that, by 2008, the UK will be about 20% international business - one reason for its recent successful drive to improve its performance in international pitches.
Gottlieb, however, argues that there's no perfect ratio. "It's a virtuous circle between local and international," he says. "There is a direct connection between great famous international brands and how you leverage that win in terms of attracting great people, and pitch locally for a fantastic domestic company."