ITV doesn’t expect it will be easy to convince regulators to approve the biggest merger in the history of U.K. broadcasting.

ITV CEO Carolyn McCall, speaking to the media on a conference call following the news that Comcast-owned Sky plans to acquire ITV’s networks and streaming business for $2.13 billion (£1.6 billion), admitted antitrust scrutiny will be rigorous.

“We expect a very through and comprehensive review [of the deal]. Which we expect will go to phase 2,” said McCall, noting that U.K. regulatory approval could take “12 to 18 months.”

A Sky-ITV deal, which brings together Britain’s leading free-to-air broadcaster with the country’s top pay-TV operator, was never going to get a quick rubber stamp. A stealth attempt by Sky’s predecessor BSkyB — then controlled by Rupert Murdoch’s News Corp. — to acquire ITV back in 2006 triggered a regulatory backlash, with antitrust watchdogs arguing the merger threatened media plurality. A year later, ITV, the BBC and Channel 4 proposed Project Kangaroo, a link-up which would have seen them launch a joint streaming venture, years before Netflix launched in the U.K.. Regulators also shot it down, arguing the deal would give the partners too much control over British TV content and stifle competition.