Sellar has appointed Paul Flexney-Briscoe as construction director for its Paddington Cube development.
Mr Flexney-Briscoe has joined from Landsec, where as project director he oversaw the delivery of the Nova scheme in Victoria.
He will take responsibility for delivering the £825m Renzo Piano-designed scheme, officially called Paddington Square.
This includes a 360,000 sq ft office building, 75,000 sq ft of retail and commercial space, and a 0.5 ha public square.
A £65m investment in the Bakerloo line station and ticket hall at Paddington is also planned.
Construction is scheduled to start in March next year, with a target completion date for the end of 2021.
In July the group will go to the High Court to appeal a ruling in November against a judicial review of the decision.
The scheme was initially proposed as a 72-storey residential tower, but this was changed to the 18-storey cube office development.
Irvine Sellar, the late chairman of Sellar Property Group, previously told Construction News the decision to convert the scheme from residential to office was partly because the high-end residential market had slowed.