Bedside lamp base ( one of apair perhaps?) I would say but....... account needs to be taken between the switch from gas to electricity! Our predecesser in Vauxhall C.H. Kempton & Sons, Albert Works did masess of oil lamps between 1874 and 1910 but mainly in the Nailsea ripple style, so I would say 1890 to 1910 in date if electric. The painting is by hand I assume....
The lip looks like a string lip which might make a fitting difficult. Photos can mislead...and no drilled hole was necessary for a lamp when bulb holders had built in torpedo switch..( An electrics historian may be able to help!
I think there is something similar in the V&A ............