The 'old' in this scene is the low building running across the centre of the photo. The North Barracks were built for the British Army in the 1840s.
The two buildings above it provide the 'new': 2 Connaught Road, the tall building at top left, was just four years old when this photo was taken. Next to it stood the Butterfield & Swire's building, then aged five.
(Detail cropped from page 64 of the new Volume 4 of 'Old Hong Photos and The Tales They Tell'. The book will be available in November 2020.)