The DfT confirmed this week that agreements signed three years ago would remain in place for 12 more months, with an option to renew them for a further year beyond that.
The decision puts an end to any imminent prospect of the DfT returning to the COI fold.
Despite last month's consolidation of COI's TV buying alongside that of the DfT within Carat, the DfT insisted this week that it would remain creatively independent.
"We will work together with COI on media buying, but intend to be independent for the foreseeable future when it comes to creative development," a DfT spokesman said.
The DfT provoked a huge controversy in 2001 when it decided to take full control of its £20m adspend. COI feared the decision could encourage other departments to follow suit, undermining its huge media buying clout.
Having been unable to persuade the DfT to return under its wing, COI is understood to be working out how the relationship can best be managed. This is expected to result in as much co-operation between the two as possible to ensure agencies' time is not wasted.
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