The masterplan, according to DfL, will 'investigate the impact of building height, scale, mass and bulk on the quality of public realm and accessibility'.
Speaking at a Greater London Authority press conference in April, Ken Livingstone described St Giles - which extends from Richard Seifert's iconic Centre Point on New Oxford Street to Covent Garden in the south and Berners Street in the west - as 'squalid' (Livingstone touts Renzo Piano to masterplan 'squalid' London district).
The London Mayor added that he was 'happy to issue CPOs' (Compulsory Purchase Orders) to ensure that 'Renzo Piano, or another famous architect working in Britain,' leads the redevelopment of the run-down area.
A DfL spokesman said the masterplan, which it describes as a 'design study' is 'about trying to find a way forward'.
He added: 'The focus will be on identifying the ways in which the scale and form of buildings would affect public space.
'This will allow the study to integrate within the planning policies of Camden and Westminster boroughs and to become a common reference for Transport for London, LDA, Design for London, the Mayor's Office and developers during future planning negotiations.'
Applicants should complete a Prequalification Questionnaire (PQQ) - available from StGilesarea@lda.gov.uk - by the end of July.