Paul France, of Madeley, had been sent an old postcard photo of the bridge showing the lamp in situ and to try to find out more posted it on a Facebook site, “Ironbridge through the Dale Yesteryear.”
There were plenty of responses and the general consensus was that it had disappeared in the 1940s.
And now historian David de Haan, a former deputy director of the Ironbridge Gorge Museum Trust, has got in touch with Paul to give what seems to be chapter and verse about the lamp, which turns out to have been one of several lamps over time which lit the way for people crossing the bridge.
David says: “My research shows that a single oil lamp was put up on the Tollhouse in 1781.
"The one on the centre of the bridge was not authorised until December 1786 and that too was oil.
"The photo shows the gas lamp which had been installed in 1840 and survived until 1946.
“The photo illustrated was taken before 1900 because that was the year the towpath railings went in.
"There is a very similar view of 1897 by Allcock (photographers) whose studio was only a couple of hundred yards away on the Wharfage.”