Under the terms of the Sky and Virgin Media agreed deal, Virgin Media would secure access to Sky's range of channels, including sports and film in high definition.
Industry figures were told to expect the deal to be finalised this week, ending more than a year of speculation surrounding VMtv. Phil Hall, head of TV at MediaCom, called the move "one of the worst-kept secrets in the industry".
The ad sales for the VMTv channels, which include Living and Bravo, are currently sold by the Virgin Media-owned sales house Ids.
Following successful completion of the acquisition, all ad sales will move to Sky Media in January 2011, leaving Ids servicing the UKTV channels, Virgin Media on-demand and Virgin Media's website. Virgin Media is currently reviewing how it operates Ids.
Ids, under the leadership of managing director James Wildman, is well respected by the buying community and agencies were informed that all deals would be honoured until the end of the year and business would continue as usual.
John Davidson, UK Head of Trading at StarcomMediaVest, said: "Ids has been in a league of its own for quite a while. They've done a great job and could have continued to do so."
He added: "The sale is part of a wider carriage deal and not just simply cutting costs. If there is any competition for jobs, it will put pressure on other people in the market."
Last month, the Competition Commission renewed its call for an overall review of the system for selling TV advertising in the UK, which could put an end to agency trading deals altogether. Davidson suggested this "could get rid of laziness but would ultimately mean clients will have to pay more".
OFT are currently considering whether the Sky-Virgin deal requires any investigation under the UK's merger control regime. One of the main precursors would be if it is expected to result in any substantial lessening of competition in the UK in Pay TV services.
Although there is no statutory time frame, the OFT confirmed a decision would usually be made upon the validity of such cases within 40 working days.
Less than two weeks ago, the OFT announced a market study into outdoor advertising after noting it was "highly concentrated" at the levels of the specialist buyers and outdoor media owners.
Further consolidation is also expected in the TV market.
Hall said: "After this deal, all eyes will turn to Five. It's absolutely inevitable that there will be more consolidation. It is very difficult to run a profitable TV company, and so the broadcasters have to look for ways to drive overheads down."
Chris Locke, UK trading director of StarcomMediaVest, said: "Five is going to be under pressure. Next year ITV, Channel 4 and Sky will be looking for more cash.
"I can see Five falling from eight per cent of the market to two or three per cent. Five needs to find a partner very swiftly or it'll be ‘au revoir'."
Some agencies are already predicting there will be just three TV sales houses this time next year, down from seven a year ago.
Chris Hayward, trading director at ZenithOptimedia, added that a possible deal between UKTV and Channel 4 was being widely touted among traders, and said: "The buying community will have concerns about the affect of competition."
The impact of further consolidation would be felt most strongly among the smaller media agencies. Hall noted how the importance of sitting within a large buying point, with stronger buying clout to leverage during the crucial trading season, would be "ever more important" in a consolidated market.
Andy Benningfield, trading director at WPP's Maxus, said: "There is a danger that it all becomes a matter of commodity and leaves a less entrepreneurial spirit in the business and less flexibility. Ids bring innovation to the market."
Richard Oliver, managing partner of investment at Interpublic agency Universal McCann, said: "We will have to wait and see. We may well see surprises ahead and there will be some things that will not be allowed to happen. This is not going to be the end of it."
Despite concerns surrounding further consolidation, many agencies concede the most recent deal does make operational sense for both Sky and Virgin Media. Hayward concluded: "Sky will be pretty pleased with themselves, but the deal also makes Virgin's offering very strong."