This Gwen Cooper costume was acquired by the production for use in 'Torchwood: Miracle Day' (2011).
The outfit consists of a brown leather jacket, pants, and purple shirt. The jacket and pants were worn in the beginning of the series, most notably in episodes 1 and 2. The pants are a stunt pair,size 29.
The shirt was worn with a different outfit later in the series. The shirt was deliberately cut in the front by the costume department, this adjustment was made on all of Gwen's shirts.