Original: When service of this line started, the section of the Kwun Tong Line from Chater to Argyle, the present-day Mong Kok station, was transferred to the Tsuen Wan Line.
Simplified: When service of this line started, the section of the Kwun Tong Line from Chater to Argyle, present-day Mong Kok station, was transferred to the Tsuen Wan Line.