I think that is a Venom aircraft of 28 Squadron in the foreground that took up gate guardian duties at RAF Kai Tak. A photo here and here of a Venom, registration WR539 at Kai Tak.
As the Wessex helicopter in the background was introduced in 1972, I surmise the photo was taken in the mid-1970s.
Source: This image came from Flickr, see https://flickr.com/photo.gne?id=44232676275
(2025 Update of URLs)
Date picture taken
1975
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