The Biography Channel has apologised after sexual references aired pre-watershed.

One viewer complained to Ofcom when three permutations of "f*ck" were heard during The Beatles' Biggest Secrets at 16:00 on November 30, 2006.

"Ofcom requested a copy of the programme," the regulator said today, "and noted in addition to “f*cking”, the words “f*ck” and “f*cked” were used; and that the programme contained references to sexual activity including “blow jobs” and “threesomes” and to drugs, and some female nudity."

The Biography Channel discovered "to its immense regret and concern" that a post-watershed version of the programme had mistakenly been scheduled for transmission in an afternoon timeslot.

"The Biography Channel confirmed that as a result of this incident, it fully revised its schedule review procedures," Ofcom reported. "All post-watershed programmes are now colour-coded and the printed schedule showing the positioning of these programmes must be signed off by the Channel Director before being uploaded for transmission. Further, staff have undergone training on the importance of the Ofcom Broadcasting Code’s requirements and of compliance with the channel’s revised procedures. The Biography Channel also offered its sincere apologies to the complainant."

Ofcom, in light of Biography's swift actions and its apology to the complainant, considers the matter resolved.