Six years ago, there wasn't much on offer for advertisers tempted to think bigger than the largest format then routinely available on outdoor - the 96-sheet. And when you were contemplating 96-sheets, the jewels in the crown were probably the Cromwell Road sites that caught the eye of business travellers and other high rollers heading for Heathrow.
Then two things happened. First, the the building wrap - a notion that started in the guerilla world of installation art but rapidly acquired commercial momentum across continental Europe - crossed the Channel. The medium was initially regarded as a one-off stunt opportunity but rapidly established itself in the mainstream as media owners such as Clear Channel and JCDecaux instigated a programme of special-build construction.
This coincided with the arrival in the UK of Van Wagner, a US media owner with a track record in large formats in New York (its first site was above Times Square), Los Angeles and Washington. Its big innovation in the UK was the Mega 96 - a format that is 50 per cent taller and wider than the standard 96-sheet billboard, bringing the dimensions up to 60ft by 15ft yet maintaining the classic 4:1 aspect ratio loved by many creatives.
Large format and banner sites are in short supply - excellent sites are a relative rarity and getting planning permission is not always easy. In any case, media owners have tended to maintain the premium nature of the product, only introducing new inventory when it offers better placement than existing sites. They are more likely to cull poorer quality plant in this sector than in any other.
There are fewer than 50 major banner sites in the UK and fewer than 100 other large-format sites (more, though, if you include all large-sized maverick formats). Revenues in this sector leaped from zero in 2000 to between £20 million and £45 million (estimates vary wildly) in 2005, but growth is likely to plateau as a result of the cautious site-build philosophies of the media owners.
What is not disputed is the disproportionately high profile these formats command. In London, the most eye-catching sites are arguably JCDecaux's M4 Tower, designed by Foster & Partners, and its 29.5-metre- high Torch, also beside the M4.
The most unmissable of the lot, however, is Fort Dunlop, a former tyre factory by the M6, which Clear Channel has turned into the largest permanent advertising space in Europe. Everything about the site is epic. The creative canvas measures 132 metres by 24 metres (an area considerably larger than a football pitch) and is formed by lacing together six separate sections on site. Printing the PVC mesh sections takes 72 hours and assembly a further 60 hours. The result is visible for miles and passed by almost 4.5 million vehicles a month. All for a media cost of £58,000 a week.
But the supersize roadside poster sites, such as Mega 96s, are becoming the mainstay of the sector - not just because they are bigger than traditional billboards but because they are often sited in better positions, are constructed from more modern materials and tend to be better maintained.
MAJOR PLAYERS: Clear Channel, Hallmark Outdoor UK, Signature Outdoor, Van Wagner, Billboard Press, blowup Media UK, Hot Fusion, Mass Communication Management
WHAT'S NEW: Back lighting
CASE STUDY - T-MOBILE FORT DUNLOP
Media owner: Clear Channel
Brief: Promote T-Mobile's Flext service
Inventory used: Fort Dunlop, the largest banner site in Europe
Target market: Everyone who would benefit from the flexibility offered by the Flext service for calls, texts, voicemails and picture messages. In a two-week period, the Fort Dunlop site is passed by more than 2.1 million vehicles.
Other media used: TV, press, radio, outdoor and online.
Client testimonial: "Fort Dunlop is unmissable - one reason why T-Mobile has advertised on the site since 2004. We've used Fort Dunlop to run six different creative executions, which have worked well as part of our wider ad strategy and provided standout by dominating the area. Our latest ad for Flext used the site to communicate our 'the world is not so rigid' message to a large audience, helping drive overall awareness for the campaign in conjunction with our other media."