Interbrew said in a statement that Templeman has decided "to take on a new challenge in a different environment outside Interbrew", though the brewer will retain him as an external consultant.
Templeman said he would not be joining a buyour bid for Bass Brewers: "I have agreed I will not join the competition." Instead he is considering job offers at venture capital firms.
Industry observers believe Templeman was dissatisfied that he had to report to Interbrew's head of Western Europe, and felt he was not being given enough independence.
He was also disappointed not to have been given a bigger role when Interbrew acquired Bass Brewers soon after buying Whitbread's brewing interests.
He lost to the head of Bass Brewers, Ian Napier in the fight to run Interbrew's combined British beer operations, and stayed as head of Whitbread because the Government finally blocked Interbrew's takeover of Bass.
At least one anonymous pub company executive said earlier this year that the Belgian brewing giant would not have had so much opposition to its takeover of Bass, culminating in the deal being blocked by the British government, if it had used Templeman more prominently. He said: "If [Interbrew] had appointed Templeman and reassured us and explained how it was going to be, then we would probably have said, 'OK, we can do business.' Instead Interbrew has behaved arrogantly towards us and not tried to communicate."
Hugo Powell, CEO of Interbrew, paid tribute to Templeman in a statement, saying: "With his vision and strategy, Miles Templeman has developed Interbrew UK into a strongly performing organisation within our western European zone. The company has been growing its market share in the take-home sector, while its position in the difficult on-trade market is stable."
Gilliland has 16 years experience with Whitbread/Interbrew UK and is given the credit for the company's customer and consumer focus strategy. Powell said: "Under the leadership of Stewart Gilliland, Interbrew UK will continue its strategy, with even greater focus and pace."