This cabinet card was listed for sale in England without any information, and only after receiving it did I see “F DOWNER WATFORD” in the lower right corner of the image. Frederick Downer (1840-1919) was the first commercial photographer in Watford, which is 15 miles (24 km) northwest of central London.
Mandolin ensembles and orchestras arose at the end of the 19th century and became quite popular in many parts of the world. I have yet to identify this group, and should note that they might not have been from Watford or even from London.
The lyre-guitar hadn’t been widely played since the 1820s, so its appearance here is unusual: