Phillips, a former director-general of the IPA, had been under pressure from several Barb shareholders angry about the delays in installing the new Barb panel and the subsequent audience figures it supplied.
This had split the Barb board, comprising representatives from ITV, the BBC, BSkyB, Channel 4, Channel 5 and the IPA, into two camps - those who supported him and those against.
The appointment of Walmsley, who was a key player in Carlton's successful bid for the ITV London weekday franchise, has led to suggestions that the ITV companies have simply appointed a place-man and made Phillips a scapegoat.
Barb has been beset with problems since it attempted to introduce a new 5,100-strong reporting panel for last January. These have included widespread regional variations on the strength of the panel and its demographic make-up. Even now the panel is well short of its target figure. ITV, Channel 4 and the BBC have had the most dramatic changes in audience figures.
Although always maintaining the panel was "robust", Barb admitted there was a problem with retaining panellists and ensuring they used the equipment correctly.
Initially the broadcasters rallied around Barb, but the first signs of dissent emerged in the Granada interim report in June when Granada's chief executive publicly stated that there was "concern with the new Barb audience measurement system".
Phillips was on holiday and no-one at Barb would comment as Campaign went to press.