The TV group, which is a joint venture between Sky Digital and A&E Television Networks in the US, plans to launch the channel on 10 July.
The chosen agency will also work across the other two channels in the portfolio -- The History Channel and The Biography Channel. The business is understood to be backed by a £1.5m spend.
Nikki Harris, the head of marketing at The History Channel, said there would be a new focus on through-the-line, rather than above-the-line, communications for both the channel launch and the rest of the portfolio.
"We're looking for an integrated agency that can handle all three accounts," she said. "We're going to be doing a lot of through-the-line work."
To date, The History Channel has worked with Leith on a project basis, but Harris said a change in strategy meant it was time to look for a new shop.
Harris said it was unlikely an agency would have been chosen before the launch of the channel on 10 July.
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