Writing on his Twitter page, Litten also revealed that a one-off special will air this year and a live show is being plotted for next year.
"I'm writing a one off special for 2010 and a 4th series for 2011. Also planning a LIVE show for 2011!" he wrote.
The ITV1 comedy started in 2007 and has since run for three series, with the most recent switching to an hour-long format.