This is a wedding photo of Ho Kom Tong's daughter, Rebecca (Ho Pak-Fong), which was taken on the steps of the main entrance to the building. To tell the world about this wedding, he displayed the Chinese characters for "daughter's wedding" on the front of his house, such that they could be read from Kowloon-side.
The photo has been included to give an idea of the sheer size and scale of 29 Conduit Road, which may not be apparent from the other photos.
To locate where it was taken, please refer to the main photo on the webpage for 29 Conduit Road. Imagine yourself standing in front of the steps in the photo (between the two buildings). There are four steps in front of you. Walk up those steps, and you'll find a mezzanine level at the back of which are more steps on which this wedding photo was taken.
I hope you can now better imagine the huge buildings towering either side of you.