The land is still in use as a car park https://www.openstreetmap.org/way/54650474

Not heard any mention of development here for about 10 years.http://news.bbc.co.uk/local/derby/hi/people_and_places/newsid_8651000/8651942.stm

May 2010
One Derby

One Derby
One Derby will be the city's largest office block

One Derby will become the city's largest ever office complex, located in the area bordered by Siddalls Road, Copeland Street and Traffic Street, close to the Westfield Centre.

    400,000 sq ft
    Six intercommunicating office blocks
    hotel, cafe and restaurant facilities
    built around a central piazza
    Full planning permission granted
    No start or completion date set 