Stephen Davies has been researching this panorama, and last night he gave RAS members an interesting talk about what he's discovered. The panorama was drawn by Lt Leopold George Heath, the gunnery lieutenant of HMS Irisis and it is usually dated to 1846. But Stephen hasn't found any record of Iris in Hong Kong that year, whereas it was here in 1845, so that's the more likely date it was drawn.
He also noted there's a copy of the engraving that the Admiralty produced available for download from the US LIbrary of Congress website, so that's what I've added here. The Library of Congress has made a very high resolution scan, so you'll want to use the zoom to see their details.
The Library's details:
Heath, Leopold George, Sir, and Great Britain. Hydrographic Department. Hong Kong &c. as seen from the anchorage. London, Hydrographic Office of the Admiralty; sold by R. B. Bate, 1847. Map. https://www.loc.gov/item/73692130/.