Developer Glenkerrin, which is behind the proposals to create around 700 new homes and 2,250m2 of shops on the 1.7ha plot of land, had originally appointed both HKR and John Pardey Architects to carry out the entire project.
The tower - to be built in the north-east corner of the site - is the landmark building of the multi-million pound scheme, and was formerly earmarked for HKR. A pair of lower mixed-use blocks designed by Pardey will not be affected by Foster's appointment.
Glenkerrin director Sean O'Gorman confirmed that he had seen HKR's tower proposal - which is in line with the London Borough of Ealing's (LBE) Urban Development Plan - but had taken the decision to appoint Foster in an effort to get LBE onside.
'We felt that we should bring in a signature architect to do a signature building,' he said.
'We met Foster and asked if [the practice] would be interested in this scheme. Of course we saw HKR's [proposal], but it was a case of who could come up with the best building. It was almost a competition, and Foster was the one we decided to run with,' added O'Gorman.
O'Gorman also revealed that two other signature architects had vied with Foster to come up with designs for the tower. The AJ understands that those architects were London-based Make and Manchester's Ian Simpson.
The Arcadia proposals, which will significantly extend the existing shopping centre, were due to be submitted for planning in May. However, at the time of going to press, and contrary to recent reports, an application has yet to be lodged with Ealing Council.
HKR would not comment, but O'Gorman claimed: 'HKR is very much involved with the scheme and everybody is working together.'
He added that a submission was 'imminent'.