The Petite sub-brand will cater for women 5"3 and under with sizes from 8 to 18. The new plus-size range called Grace includes sizes 18 to 28.
Each range will consist of 45 pieces. Petite will go into 25 stores and Grace will hit 50 stores from March 31.
Key pieces in the Grace collection include black fitted trousers for £10, chestnut pleat shirt at £15 and white casual trousers at £15.
The Petite collection features a lime green smock top for £10, a hot pink crochet button down cardigan for £20, white cropped denim jeans at £15, and a navy cotton cross over sundress for £18.