He departed the company some months ago, according to Expectation.
The move was first reported by Deadline today.
Samwell-Smith was previously managing director of the Endemol Shine-owned Initial, where he had worked since 1997 and produced Big Brother.
“It was by mutual agreement that Nick left Expectation to pursue other projects. We wish him well in his future endeavors,” said a spokesperson for Expectation, in a statement.
Expectation has not replaced Samwell-Smith, with creative director duties falling solely on Mather since his departure.